diff --git a/RELEASE_NOTES.md b/RELEASE_NOTES.md
index ef35dfe..384b0a2 100644
--- a/RELEASE_NOTES.md
+++ b/RELEASE_NOTES.md
@@ -14,6 +14,8 @@
 * The `ReportingApiClient` exposes the option to resample the data, with its
 `resolution` represented in seconds and its default set to `None` (no resampling).
 
+* An API key for authorization can now be passed to the `ReportingApiClient`.
+
 ## Bug Fixes
 
 <!-- Here goes notable bug fixes that are worth a special mention or explanation -->
diff --git a/examples/client.py b/examples/client.py
index 2a5fea2..ed436a7 100644
--- a/examples/client.py
+++ b/examples/client.py
@@ -54,6 +54,12 @@ def main() -> None:
     parser.add_argument(
         "--display", choices=["iter", "df", "dict"], help="Display format", default="df"
     )
+    parser.add_argument(
+        "--key",
+        type=str,
+        help="API key",
+        default=None,
+    )
     args = parser.parse_args()
     asyncio.run(
         run(
@@ -65,6 +71,7 @@ def main() -> None:
             args.resolution,
             page_size=args.psize,
             service_address=args.url,
+            key=args.key,
             display=args.display,
         )
     )
@@ -80,6 +87,7 @@ async def run(
     resolution: int,
     page_size: int,
     service_address: str,
+    key: str,
     display: str,
 ) -> None:
     """Test the ReportingApiClient.
@@ -93,12 +101,13 @@ async def run(
         resolution: resampling resolution in sec
         page_size: page size
         service_address: service address
+        key: API key
         display: display format
 
     Raises:
         ValueError: if display format is invalid
     """
-    client = ReportingApiClient(service_address)
+    client = ReportingApiClient(service_address, key)
 
     metrics = [Metric[mn] for mn in metric_names]
 
diff --git a/src/frequenz/client/reporting/_client.py b/src/frequenz/client/reporting/_client.py
index 635afb5..e451392 100644
--- a/src/frequenz/client/reporting/_client.py
+++ b/src/frequenz/client/reporting/_client.py
@@ -115,14 +115,16 @@ def next_page_token(self) -> str | None:
 class ReportingApiClient:
     """A client for the Reporting service."""
 
-    def __init__(self, service_address: str):
+    def __init__(self, service_address: str, key: str | None = None) -> None:
         """Create a new Reporting client.
 
         Args:
             service_address: The address of the Reporting service.
+            key: The API key for the authorization.
         """
         self._grpc_channel = grpcaio.insecure_channel(service_address)
         self._stub = ReportingStub(self._grpc_channel)
+        self._metadata = (("key", key),) if key else ()
 
     # pylint: disable=too-many-arguments
     async def list_single_component_data(
@@ -301,9 +303,12 @@ async def _fetch_page(
                 filter=list_filter,
                 pagination_params=pagination_params,
             )
+            print(self._metadata)
             response = await cast(
                 Awaitable[PBListMicrogridComponentsDataResponse],
-                self._stub.ListMicrogridComponentsData(request),
+                self._stub.ListMicrogridComponentsData(
+                    request, metadata=self._metadata
+                ),
             )
         except grpcaio.AioRpcError as e:
             print(f"RPC failed: {e}")