diff --git a/run_start_metadata_schema.json b/run_start_metadata_schema.json
new file mode 100644
index 0000000..41cc027
--- /dev/null
+++ b/run_start_metadata_schema.json
@@ -0,0 +1,79 @@
+{
+  "$schema": "https://json-schema.org/draft/2020-12/schema",
+  "$id": "https://github.com/ISISComputingGroup/DataStreaming/blob/main/run_start_metadata_schema.json",
+  "title": "run_start_metadata_schema",
+  "description": "Schema for run start metadata used at ISIS for kafka_dae_diagnostics",
+  "type": "object",
+  "properties": {
+    "num_periods": {
+      "description": "The total number of periods for this run, 1 indexed.",
+      "type": "integer"
+    },
+    "max_time_channels": {
+      "description": "The maximum number of time channels for this run.",
+      "type": "integer"
+    },
+    "time_regimes": {
+      "description": "The time regimes for this run.",
+      "type": "array",
+      "minItems": 1,
+      "items": {
+        "type": "array",
+        "description": "time regime rows",
+        "items": {
+          "$comment": "Either linear time regime rows, or an arbitrary list of bin-edges.",
+          "oneOf": [
+            {
+              "type": "object",
+              "description": "time regime row",
+              "properties": {
+                "from": {
+                  "type": "number"
+                },
+                "to": {
+                  "type": "number"
+                },
+                "steps": {
+                  "type": "number"
+                },
+                "mode": {
+                  "enum": [
+                    "dT = C",
+                    "dT/T = C",
+                    "dT/T**2 = C",
+                    "Shifted"
+                  ]
+                }
+              }
+            },
+            {
+              "type": "integer"
+            }
+          ]
+        }
+      }
+    },
+    "vetos": {
+      "description": "The vetos for this run",
+      "type": "array",
+      "minItems": 1,
+      "items": {
+        "type": "object",
+        "properties": {
+          "name": {
+            "type": "string"
+          },
+          "enabled": {
+            "type": "boolean"
+          }
+        }
+      }
+    }
+  },
+  "required": [
+    "num_periods",
+    "num_time_channels",
+    "time_regimes",
+    "vetos"
+  ]
+}
\ No newline at end of file