diff --git a/CHANGELOG.md b/CHANGELOG.md
index 83c1da04..4fdace7a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -16,6 +16,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   - `recovery-form` to link to the credentials recovery page.
 - `GET /me`: New Relation types `alternate` and `related` for user-specific external pages. [#404](https://github.com/Open-EO/openeo-api/issues/404)
 - `GET /credentials/oidc`: Allow `authorization_code` and `urn:ietf:params:oauth:grant-type:device_code` (both without PKCE) as grants for `default_clients`. [#410](https://github.com/Open-EO/openeo-api/issues/410)
+- Added `GET /processing_options` to define the parameters that can be submitted when creating jobs or services. [#276](https://github.com/Open-EO/openeo-api/issues/276)
 - `GET /jobs` and `GET /jobs/{job_id}`: Added a links property that can for example link to results and logs. [#453](https://github.com/Open-EO/openeo-api/issues/453)
 - `GET /jobs/{job_id}/results`:
   - Recommendation to add a link with relation type `canonical` which points to a signed URL with the same content as the response. [#397](https://github.com/Open-EO/openeo-api/issues/397)
diff --git a/openapi.yaml b/openapi.yaml
index bc10ad7e..107cbcec 100644
--- a/openapi.yaml
+++ b/openapi.yaml
@@ -2397,6 +2397,43 @@ paths:
           $ref: '#/components/responses/client_error_auth'
         5XX:
           $ref: '#/components/responses/server_error'
+  /processing_options:
+    get:
+      summary: Additional processing options
+      operationId: list-processing-options
+      description: |-
+        Lists additional custom processing options that a back-end offers for the
+        different processing modes (synchronous processing, batch jobs, secondary web services).
+
+        The options specified here can be added to the corresponding `POST` requests
+        at the top-level of the object that is sent as the payload.
+        All options SHOULD explicitly be made optional with reasonable defaults
+        as otherwise the interoperability between the implementations decreases.
+      tags:
+        - Capabilities
+        - Data Processing
+        - Batch Jobs
+        - Secondary Services
+      security:
+        - {}
+        - Bearer: []
+      responses:
+        '200':
+          description: >-
+            An object with a list of parameters per processing mode.
+          content:
+            application/json:
+              schema:
+                description: Processing parameters per processing mode.
+                type: object
+                properties:
+                  create_job_parameters:
+                    $ref: '#/components/schemas/processing_create_parameters'
+                  create_service_parameters:
+                    $ref: '#/components/schemas/processing_create_parameters'
+                  create_synchronous_parameters:
+                    $ref: '#/components/schemas/processing_create_parameters'
+
   /service_types:
     get:
       summary: Supported secondary web service protocols
@@ -5706,7 +5743,23 @@ components:
             the same level. For example, if type is string, then default can be
             "foo" but cannot be 1. See [JSON Schema draft-07](https://json-schema.org/draft-07/json-schema-validation.html#rfc.section.10.2).
       allOf:
-        - $ref: '#/components/schemas/process_json_schema'
+        - $ref: '#/components/schemas/json_schema'
+    processing_create_parameters:
+      title: Creation Parameters
+      description: |-
+        List of additional custom parameters that a back-end offers during the creation
+        of batch jobs (`POST /jobs`) and secondary web services (`POST /services`) respectively.
+      type: array
+      items:
+        $ref: '#/components/schemas/parameter'
+      example:
+        - name: memory
+          description: Maximum amount of memory that will be allocated for processing, in gigabytes.
+          optional: true
+          default: 32
+          schema:
+            type: integer
+            minimum: 1
     error:
       title: General Error
       description: >-