diff --git a/temporian/beam/evaluation.py b/temporian/beam/evaluation.py
index e0817b8c8..6353f5286 100644
--- a/temporian/beam/evaluation.py
+++ b/temporian/beam/evaluation.py
@@ -126,33 +126,33 @@ def run_multi_io(
 
     data = {**inputs}
 
-    num_operators = len(schedule.ordered_operators)
-    for operator_idx, operator in enumerate(schedule.ordered_operators):
-        operator_def = operator.definition()
+    num_steps = len(schedule.steps)
+    for step_idx, step in enumerate(schedule.steps):
+        operator_def = step.op.definition()
 
         print("=============================", file=sys.stderr)
         print(
-            f"{operator_idx+1} / {num_operators}: Run {operator}",
+            f"{step_idx+1} / {num_steps}: Run {step.op}",
             file=sys.stderr,
         )
 
         # Construct operator inputs
         operator_inputs = {
             input_key: data[input_node]
-            for input_key, input_node in operator.inputs.items()
+            for input_key, input_node in step.op.inputs.items()
         }
 
         # Get Beam implementation
         implementation_cls = implementation_lib.get_implementation_class(
             operator_def.key
         )
-        implementation = implementation_cls(operator)
+        implementation = implementation_cls(step.op)
 
         # Add implementation to Beam pipeline
         operator_outputs = implementation(**operator_inputs)
 
         # Collect outputs
-        for output_key, output_node in operator.outputs.items():
+        for output_key, output_node in step.op.outputs.items():
             data[output_node] = operator_outputs[output_key]
 
     return {output: data[output] for output in outputs}
diff --git a/temporian/core/evaluation.py b/temporian/core/evaluation.py
index 570ba9f19..2ac79deef 100644
--- a/temporian/core/evaluation.py
+++ b/temporian/core/evaluation.py
@@ -24,7 +24,7 @@
 from temporian.implementation.numpy import evaluation as np_eval
 from temporian.implementation.numpy.data.event_set import EventSet
 from temporian.core.graph import infer_graph
-from temporian.core.schedule import Schedule
+from temporian.core.schedule import Schedule, ScheduleStep
 from temporian.core.operators.leak import LeakOperator
 
 EvaluationQuery = Union[
@@ -143,7 +143,7 @@ def run(
 
     if verbose == 1:
         print(
-            f"Run {len(schedule.ordered_operators)} operators",
+            f"Run {len(schedule.steps)} operators",
             file=sys.stderr,
         )
 
@@ -208,7 +208,8 @@ def build_schedule(
     # Operators ready to be computed (i.e. ready to be added to "planned_ops")
     # as all their inputs are already computed by "planned_ops" or specified by
     # "inputs".
-    ready_ops: Set[Operator] = set()
+    ready_ops: List[Operator] = []
+    ready_ops_set: Set[Operator] = set()
 
     # "node_to_op[e]" is the list of operators with node "e" as input.
     node_to_op: Dict[EventSetNode, List[Operator]] = defaultdict(lambda: [])
@@ -222,25 +223,50 @@ def build_schedule(
     for op in graph.operators:
         num_pending_inputs = 0
         for input_node in op.inputs.values():
+            node_to_op[input_node].append(op)
             if input_node in graph.inputs:
                 # This input is already available
                 continue
-            node_to_op[input_node].append(op)
             num_pending_inputs += 1
         if num_pending_inputs == 0:
             # Ready to be scheduled
-            ready_ops.add(op)
+            ready_ops.append(op)
+            ready_ops_set.add(op)
         else:
             # Some of the inputs are missing.
             op_to_num_pending_inputs[op] = num_pending_inputs
 
+    # Make evaluation order deterministic.
+    #
+    # Execute the op with smallest internal ordered id first.
+    ready_ops.sort(key=lambda op: op._internal_ordered_id, reverse=True)
+
     # Compute the schedule
     while ready_ops:
         # Get an op ready to be scheduled
         op = ready_ops.pop()
+        ready_ops_set.remove(op)
+
+        # Nodes released after the op is executed
+        released_nodes = []
+        for input in op.inputs.values():
+            if input in outputs:
+                continue
+            if input not in node_to_op:
+                continue
+            # The list of ops that depends on this input (including the current
+            # op "op").
+            input_usage = node_to_op[input]
+            input_usage.remove(op)
+
+            if not input_usage:
+                released_nodes.append(input)
+                del node_to_op[input]
 
         # Schedule the op
-        schedule.ordered_operators.append(op)
+        schedule.steps.append(
+            ScheduleStep(op=op, released_nodes=released_nodes)
+        )
 
         # Update all the ops that depends on "op". Enlist the ones that are
         # ready to be computed
@@ -256,7 +282,8 @@ def build_schedule(
 
                 if num_missing_inputs == 0:
                     # "new_op" can be computed
-                    ready_ops.add(new_op)
+                    ready_ops.append(new_op)
+                    ready_ops_set.add(new_op)
                     del op_to_num_pending_inputs[new_op]
 
     assert not op_to_num_pending_inputs
diff --git a/temporian/core/operators/base.py b/temporian/core/operators/base.py
index 72a704401..609169ae3 100644
--- a/temporian/core/operators/base.py
+++ b/temporian/core/operators/base.py
@@ -72,6 +72,8 @@ def __exit__(self, exc_type, exc_val, traceback):
 class Operator(ABC):
     """Interface definition and common logic for operators."""
 
+    next_internal_id: int = 0
+
     def __init__(self):
         self._inputs: Dict[str, EventSetNode] = {}
         self._outputs: Dict[str, EventSetNode] = {}
@@ -81,10 +83,18 @@ def __init__(self):
             attr.key: attr.type for attr in self._definition.attributes
         }
 
+        # Id of the operator object such that an operator A instantiated before
+        # an operator B will have a smaller _internal_ordered_id.
+        #
+        # _internal_ordered_id is used to ensure the deterministic graph
+        # evaluation.
+        self._internal_ordered_id = Operator.next_internal_id
+        Operator.next_internal_id += 1
+
     def __repr__(self):
         return (
-            f"Operator(key={self.definition().key!r}, id={id(self)!r},"
-            f" attributes={self.attributes!r})"
+            f"Operator(key={self.definition().key!r},"
+            f" id={self._internal_ordered_id}, attributes={self.attributes!r})"
         )
 
     @property
diff --git a/temporian/core/schedule.py b/temporian/core/schedule.py
index f5924ceef..c9f59c7b0 100644
--- a/temporian/core/schedule.py
+++ b/temporian/core/schedule.py
@@ -19,7 +19,15 @@
 from temporian.core.operators.base import Operator
 
 
+@dataclass
+class ScheduleStep:
+    op: Operator
+
+    # List of nodes that will not be used anymore after "op" is executed.
+    released_nodes: List[EventSetNode]
+
+
 @dataclass
 class Schedule:
-    ordered_operators: List[Operator] = field(default_factory=list)
+    steps: List[ScheduleStep] = field(default_factory=list)
     input_nodes: Set[EventSetNode] = field(default_factory=set)
diff --git a/temporian/core/test/evaluation_test.py b/temporian/core/test/evaluation_test.py
index fd178a1b3..916bee118 100644
--- a/temporian/core/test/evaluation_test.py
+++ b/temporian/core/test/evaluation_test.py
@@ -29,13 +29,13 @@ def test_schedule_trivial(self):
         schedule = evaluation.build_schedule(
             inputs={a}, outputs={b.outputs["output"]}
         )
-        self.assertEqual(schedule.ordered_operators, [b])
+        self.assertEqual(schedule.steps, [evaluation.ScheduleStep(b, [a])])
 
     def test_schedule_empty(self):
         a = utils.create_input_node()
 
         schedule = evaluation.build_schedule(inputs={a}, outputs={a})
-        self.assertEqual(schedule.ordered_operators, [])
+        self.assertEqual(schedule.steps, [])
 
     def test_schedule_two_delayed_inputs(self):
         i1 = utils.create_input_node()
@@ -46,9 +46,15 @@ def test_schedule_two_delayed_inputs(self):
         schedule = evaluation.build_schedule(
             inputs={i1, i2}, outputs={o3.outputs["output"]}
         )
-        self.assertTrue(
-            (schedule.ordered_operators == [o2, o1, o3])
-            or (schedule.ordered_operators == [o1, o2, o3])
+        self.assertEqual(
+            schedule.steps,
+            [
+                evaluation.ScheduleStep(o1, [i1]),
+                evaluation.ScheduleStep(o2, [i2]),
+                evaluation.ScheduleStep(
+                    o3, [o1.outputs["output"], o2.outputs["output"]]
+                ),
+            ],
         )
 
     def test_schedule_basic(self):
@@ -62,9 +68,16 @@ def test_schedule_basic(self):
             inputs={i1, i3},
             outputs={o5.outputs["output_1"], o4.outputs["output"]},
         )
-        self.assertTrue(
-            (schedule.ordered_operators == [o2, o4, o5])
-            or (schedule.ordered_operators == [o4, o2, o5])
+
+        self.assertEqual(
+            schedule.steps,
+            [
+                evaluation.ScheduleStep(op=o2, released_nodes=[i1]),
+                evaluation.ScheduleStep(
+                    op=o4, released_nodes=[o2.outputs["output"], i3]
+                ),
+                evaluation.ScheduleStep(op=o5, released_nodes=[]),
+            ],
         )
 
     def test_schedule_mid_chain(self):
@@ -77,7 +90,35 @@ def test_schedule_mid_chain(self):
         schedule = evaluation.build_schedule(
             inputs={o3.outputs["output"]}, outputs={o5.outputs["output"]}
         )
-        self.assertEqual(schedule.ordered_operators, [o4, o5])
+
+        self.assertEqual(
+            schedule.steps,
+            [
+                evaluation.ScheduleStep(
+                    op=o4, released_nodes=[o3.outputs["output"]]
+                ),
+                evaluation.ScheduleStep(
+                    op=o5, released_nodes=[o4.outputs["output"]]
+                ),
+            ],
+        )
+
+    def test_schedule_interm_results(self):
+        i1 = utils.create_input_node()
+        o2 = utils.OpI1O1(i1)
+        o3 = utils.OpI1O1(o2.outputs["output"])
+
+        schedule = evaluation.build_schedule(
+            inputs={i1}, outputs={o3.outputs["output"], o2.outputs["output"]}
+        )
+
+        self.assertEqual(
+            schedule.steps,
+            [
+                evaluation.ScheduleStep(op=o2, released_nodes=[i1]),
+                evaluation.ScheduleStep(op=o3, released_nodes=[]),
+            ],
+        )
 
     def test_run_value(self):
         i1 = utils.create_input_node()
diff --git a/temporian/implementation/numpy/evaluation.py b/temporian/implementation/numpy/evaluation.py
index 23da73d74..a9e576c04 100644
--- a/temporian/implementation/numpy/evaluation.py
+++ b/temporian/implementation/numpy/evaluation.py
@@ -46,9 +46,9 @@ def run_schedule(
     """
     data = {**inputs}
 
-    num_operators = len(schedule.ordered_operators)
-    for operator_idx, operator in enumerate(schedule.ordered_operators):
-        operator_def = operator.definition()
+    num_steps = len(schedule.steps)
+    for step_idx, step in enumerate(schedule.steps):
+        operator_def = step.op.definition()
 
         # Get implementation
         implementation_cls = implementation_lib.get_implementation_class(
@@ -56,28 +56,25 @@ def run_schedule(
         )
 
         # Instantiate implementation
-        implementation = implementation_cls(operator)
+        implementation = implementation_cls(step.op)
 
         if verbose == 1:
             print(
-                (
-                    f"    {operator_idx+1} / {num_operators}:"
-                    f" {operator.operator_key()}"
-                ),
+                f"    {step_idx+1} / {num_steps}: {step.op.operator_key()}",
                 file=sys.stderr,
                 end="",
             )
         elif verbose >= 2:
             print("=============================", file=sys.stderr)
             print(
-                f"{operator_idx+1} / {num_operators}: Run {operator}",
+                f"{step_idx+1} / {num_steps}: Run {step.op}",
                 file=sys.stderr,
             )
 
         # Construct operator inputs
         operator_inputs = {
             input_key: data[input_node]
-            for input_key, input_node in operator.inputs.items()
+            for input_key, input_node in step.op.inputs.items()
         }
 
         if verbose >= 2:
@@ -98,11 +95,14 @@ def run_schedule(
             print(f"Duration: {end_time - begin_time} s", file=sys.stderr)
 
         # materialize data in output nodes
-        for output_key, output_node in operator.outputs.items():
+        for output_key, output_node in step.op.outputs.items():
             output_evset = operator_outputs[output_key]
             output_evset._internal_node = output_node
             data[output_node] = output_evset
 
-    # TODO: Only return the required data.
-    # TODO: Un-allocate not used anymore object.
+        # Release unused memory
+        for node in step.released_nodes:
+            assert node in data
+            del data[node]
+
     return data