diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 497ac1e..9426240 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -43,5 +43,5 @@ jobs:
 
       - name: Run test suite
         env:
-          TOKEN: ${{ secrets.TOKEN }}
+          ONC_TOKEN: ${{ secrets.ONC_TOKEN }}
         run: tox --skip-pkg-install
diff --git a/.github/workflows/doc.yml b/.github/workflows/doc.yml
index a1ab6e6..321d5ba 100644
--- a/.github/workflows/doc.yml
+++ b/.github/workflows/doc.yml
@@ -25,21 +25,21 @@ jobs:
 
       - name: Build HTML
         env:
-          TOKEN: ${{ secrets.TOKEN }}
+          ONC_TOKEN: ${{ secrets.ONC_TOKEN }}
         run: |
           # Convert the dummy token to the real token for executing the jupyter notebook
-          sed -i "s/YOUR_TOKEN/$TOKEN/" doc/source/Tutorial/onc_Library_Tutorial.ipynb
+          sed -i "s/YOUR_TOKEN/$ONC_TOKEN/" doc/source/Tutorial/onc_Library_Tutorial.ipynb
           sed -i '/nb_execution_mode = "off"/d' doc/source/conf.py # enable executing jupyter notebook
           sphinx-build -W doc/source doc/build/html
 
       - name: Remove ampersand encoding and token in the generated html
         env:
-          TOKEN: ${{ secrets.TOKEN }}
+          ONC_TOKEN: ${{ secrets.ONC_TOKEN }}
         run: |
           # See issues about ampersand encoding at https://github.com/executablebooks/MyST-Parser/issues/760
           sed -i 's/amp;//g' doc/build/html/Tutorial/Oceans_3.0_API_Tutorial.html
           # Some cell outputs in the Jupyter notebook contain the token
-          sed -i "s/$TOKEN/YOUR_TOKEN/g" doc/build/html/Tutorial/onc_Library_Tutorial.html
+          sed -i "s/$ONC_TOKEN/YOUR_TOKEN/g" doc/build/html/Tutorial/onc_Library_Tutorial.html
 
       - name: Run ghp-import to generate GitHub Pages
         run: |
diff --git a/README.md b/README.md
index 92551ce..5422d6e 100644
--- a/README.md
+++ b/README.md
@@ -60,6 +60,7 @@ The example below uses the `getLocations` method to search for locations that in
 from onc import ONC
 
 onc = ONC("YOUR_TOKEN")
+onc = ONC() # This works if the env variable "ONC_TOKEN" is set
 
 onc.getLocations({"locationName": "Burrard"})
 ```
diff --git a/doc/source/Tutorial/onc_Library_Tutorial.ipynb b/doc/source/Tutorial/onc_Library_Tutorial.ipynb
index 4159578..a6c7882 100644
--- a/doc/source/Tutorial/onc_Library_Tutorial.ipynb
+++ b/doc/source/Tutorial/onc_Library_Tutorial.ipynb
@@ -78,6 +78,8 @@
     "\n",
     "to indicate that you want to see verbose messages after running each method, and you want the download directory to be \"./YOUR_DIRECTORY\" instead of the default \"./output\" when calling methods that involve downloading files like `orderDataProduct` and `downloadArchivefile`.\n",
     "\n",
+    "You can also use `onc = ONC()` if you have set the env variable \"ONC_TOKEN\".\n",
+    "\n",
     "For more information, check the API reference of the [ONC](https://oceannetworkscanada.github.io/api-python-client/autoapi/onc/index.html#onc.ONC) class.\n"
    ]
   },
diff --git a/src/onc/onc.py b/src/onc/onc.py
index 922f983..facdc41 100644
--- a/src/onc/onc.py
+++ b/src/onc/onc.py
@@ -2,6 +2,7 @@
 
 import datetime
 import json
+import os
 import re
 from pathlib import Path
 
@@ -20,8 +21,9 @@ class ONC:
 
     Parameters
     ----------
-    token : str
+    token : str | None, default None
         The ONC API token, which could be retrieved at https://data.oceannetworks.ca/Profile once logged in.
+        If None, the token is read from the environment variable ``ONC_TOKEN``.
     production : boolean, default True
         Whether the ONC Production server URL is used for service requests.
 
@@ -44,19 +46,27 @@ class ONC:
     Examples
     --------
     >>> from onc import ONC
+    >>> onc = ONC()  # Only if you set the env variable "ONC_TOKEN" # doctest: +SKIP
     >>> onc = ONC("YOUR_TOKEN_HERE")  # doctest: +SKIP
     >>> onc = ONC("YOUR_TOKEN_HERE", showInfo=True, outPath="onc-files")  # doctest: +SKIP
     """  # noqa: E501
 
     def __init__(
         self,
-        token,
+        token: str | None = None,
         production: bool = True,
         showInfo: bool = False,
-        showWarning: bool = False,
+        showWarning: bool = True,
         outPath: str | Path = "output",
         timeout: int = 60,
     ):
+        if token is None or token == "":
+            token = os.environ.get("ONC_TOKEN")
+        if token is None or token == "":
+            raise ValueError(
+                "ONC API token is required. Please provide it as the first argument, "
+                "or set it as the environment variable 'ONC_TOKEN'."
+            )
         self.token = re.sub(r"[^a-zA-Z0-9\-]+", "", token)
         self.showInfo = showInfo
         self.showWarning = showWarning
diff --git a/tests/conftest.py b/tests/conftest.py
index 3808280..12d434d 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -6,7 +6,6 @@
 from onc import ONC
 
 load_dotenv(override=True)
-token = os.getenv("TOKEN")
 is_prod = os.getenv("ONC_ENV", "PROD") == "PROD"
 
 
@@ -17,7 +16,7 @@ def pytest_configure():
 
 @pytest.fixture
 def requester(tmp_path) -> ONC:
-    return ONC(token, is_prod, outPath=tmp_path)
+    return ONC(production=is_prod, outPath=tmp_path)
 
 
 @pytest.fixture(scope="session")
@@ -51,7 +50,7 @@ def update_file_with_token_and_qa(tmp_py: Path) -> None:
         index = contents.index('onc = ONC("YOUR_TOKEN")\n')
         contents.insert(
             index + 1,
-            f"onc.token, onc.production, onc.timeout = '{token}', False, 300\n",  # noqa: E501
+            f"onc.token, onc.production, onc.timeout = '{os.getenv('ONC_TOKEN')}', False, 300\n",  # noqa: E501
         )
         with open(tmp_py, "w") as f:
             f.writelines(contents)
diff --git a/tox.ini b/tox.ini
index 63b765a..8784bd0 100644
--- a/tox.ini
+++ b/tox.ini
@@ -12,7 +12,7 @@ deps =
     python-dotenv
     pytest
     pytest-cov
-passenv = TOKEN
+passenv = ONC_TOKEN
 commands =
     pytest --cov=onc