diff --git a/.github/workflows/fmu-ensemble.yml b/.github/workflows/fmu-ensemble.yml
index 98b0ca0f..a0e65ed0 100644
--- a/.github/workflows/fmu-ensemble.yml
+++ b/.github/workflows/fmu-ensemble.yml
@@ -42,7 +42,7 @@ jobs:
 
       - name: 📦 Install test dependencies
         run: |
-          pip install ecl2df
+          pip install res2df
           pip install .[tests,docs]
 
       - name: 🧾 List all installed packages
diff --git a/docs/advancedusage.rst b/docs/advancedusage.rst
index 6dff3f93..3437a4c9 100644
--- a/docs/advancedusage.rst
+++ b/docs/advancedusage.rst
@@ -253,15 +253,15 @@ in the realization object to use, potentially only the directory).
    :header-rows: 1
 
 where PORV and VOLUME are sums over each zone, Z is the minimum (thus apex pr.
-zone) and PERMX is an arithmetic mean. In the language of `ecl2df
-<https://equinor.github.io/ecl2df/>`_ this could be done with a code like this:
+zone) and PERMX is an arithmetic mean. In the language of `res2df
+<https://equinor.github.io/res2df/>`_ this could be done with a code like this:
 
 .. code-block:: python
 
-   from ecl2df import grid, EclFiles
+   from res2df import grid, ResdataFiles
 
-   eclfiles = EclFiles('MYDATADECK.DATA')  # There is a file zones.lyr alongside this.
-   grid_df = grid.df(eclfiles)  # Produce a dataframe with one row pr. cell
+   resdatafiles = ResdataFiles('MYDATADECK.DATA')  # There is a file zones.lyr alongside this.
+   grid_df = grid.df(resdatafiles)  # Produce a dataframe with one row pr. cell
    my_aggregators = {'PORV': 'sum', 'VOLUME': 'sum', 'Z': 'min', 'PERMX': 'mean'}
    stats_df = grid_df.groupby("ZONE").agg(my_aggregators)
    print(stats_df)
@@ -269,10 +269,10 @@ zone) and PERMX is an arithmetic mean. In the language of `ecl2df
 
 ``ScratchRealization`` objects contain the methods ``runpath()`` which will give
 the full path to the directory  the realization resides in, this can be used
-freely by your function.  For easier coupling with ecl2df, the function
-``get_eclfiles()`` is provided.
+freely by your function.  For easier coupling with res2df, the function
+``get_resdatafiles()`` is provided.
 
-To be able to inject the ecl2df lines above into the API of fmu.ensemble and the
+To be able to inject the res2df lines above into the API of fmu.ensemble and the
 :py:meth:`apply() <fmu.ensemble.ensemble.ScratchEnsemble.apply>` function, we
 need to to put it into a wrapper function.  This wrapper function will always
 receive a Realization object as a named argument, and it must return a
@@ -280,7 +280,7 @@ dataframe. The wrapper function can look like this:
 
 .. code-block:: python
 
-   from ecl2df import grid, EclFiles
+   from res2df import grid, ResdataFiles
 
    def my_realization_stats(args):
       """A custom function for performing a particular calculation
@@ -290,8 +290,8 @@ dataframe. The wrapper function can look like this:
          args (dict): A dictionary with parameters to my custom function.
              The keys 'realization' and 'localpath' are reserved for fmu.ensemble."""
       realization = args["realization"]  # Provided by fmu.ensemble apply()
-      eclfiles = realization.get_eclfiles()
-      grid_df = grid.df(eclfiles)
+      resdatafiles = realization.get_resdatafiles()
+      grid_df = grid.df(resdatafiles)
       my_aggregators = {'PORV': 'sum', 'VOLUME': 'sum', 'Z': 'min', 'PERMX': 'mean'}
       stats_df = grid_df.groupby("ZONE").agg(my_aggregators)
       return stats_df.reset_index()  # Zone names are in the index, lost if not reset.
diff --git a/src/fmu/ensemble/realization.py b/src/fmu/ensemble/realization.py
index 95c1f21c..a7a5064b 100644
--- a/src/fmu/ensemble/realization.py
+++ b/src/fmu/ensemble/realization.py
@@ -31,13 +31,13 @@
 from .util.rates import compute_volumetric_rates
 from .virtualrealization import VirtualRealization
 
-HAVE_ECL2DF = False
+HAVE_RES2DF = False
 try:
-    import ecl2df
+    import res2df
 
-    HAVE_ECL2DF = True
+    HAVE_RES2DF = True
 except ImportError:
-    HAVE_ECL2DF = False
+    HAVE_RES2DF = False
 
 logger = logging.getLogger(__name__)
 
@@ -844,9 +844,9 @@ def parameters(self):
         """
         return self.data["parameters.txt"]
 
-    def get_eclfiles(self):
+    def get_resdatafiles(self):
         """
-        Return an ecl2df.EclFiles object to connect to the ecl2df package
+        Return an res2df.ResdataFiles object to connect to the res2df package
 
         If autodiscovery, it will search for a DATA file in
         the standard location eclipse/model/...DATA.
@@ -858,10 +858,10 @@ def get_eclfiles(self):
             >>> real.find_files("eclipse/model/MYMODELPREDICTION.DATA")
 
         Returns:
-            ecl2df.EclFiles. None if nothing found
+            res2df.ResdataFiles. None if nothing found
         """
-        if not HAVE_ECL2DF:
-            logger.warning("ecl2df not installed. Skipping")
+        if not HAVE_RES2DF:
+            logger.warning("res2df not installed. Skipping")
             return None
         data_file_row = self.files[self.files["FILETYPE"] == "DATA"]
         data_filename = None
@@ -887,7 +887,7 @@ def get_eclfiles(self):
             return None
         if not os.path.exists(data_filename):
             return None
-        return ecl2df.EclFiles(data_filename)
+        return res2df.ResdataFiles(data_filename)
 
     def get_eclsum(self, cache=True, include_restart=True):
         """
diff --git a/tests/test_ensemble.py b/tests/test_ensemble.py
index 381d15c7..e52da755 100644
--- a/tests/test_ensemble.py
+++ b/tests/test_ensemble.py
@@ -1,4 +1,5 @@
 """Testing fmu-ensemble."""
+
 # pylint: disable=protected-access
 
 import logging
diff --git a/tests/test_realization.py b/tests/test_realization.py
index 690f013a..07417767 100644
--- a/tests/test_realization.py
+++ b/tests/test_realization.py
@@ -1,4 +1,5 @@
 """Testing fmu-ensemble."""
+
 # pylint: disable=protected-access
 
 import datetime
diff --git a/tests/test_ecl2df.py b/tests/test_res2df.py
similarity index 62%
rename from tests/test_ecl2df.py
rename to tests/test_res2df.py
index 227c77eb..151930c1 100644
--- a/tests/test_ecl2df.py
+++ b/tests/test_res2df.py
@@ -1,4 +1,4 @@
-"""Testing incorporation of ecl2df in fmu-ensemble."""
+"""Testing incorporation of res2df in fmu-ensemble."""
 
 import logging
 import os
@@ -6,19 +6,19 @@
 import pytest
 from fmu.ensemble import ScratchEnsemble, ScratchRealization
 
-HAVE_ECL2DF = True
+HAVE_RES2DF = True
 try:
-    import ecl2df
+    import res2df
 except ImportError:
-    HAVE_ECL2DF = False
+    HAVE_RES2DF = False
 
 logger = logging.getLogger(__name__)
 
 
-def test_ecl2df_real():
-    """Check that we can utilize ecl2df on single realizations"""
+def test_res2df_real():
+    """Check that we can utilize res2df on single realizations"""
 
-    if not HAVE_ECL2DF:
+    if not HAVE_RES2DF:
         pytest.skip()
 
     if "__file__" in globals():
@@ -29,15 +29,15 @@ def test_ecl2df_real():
     realdir = os.path.join(testdir, "data/testensemble-reek001", "realization-0/iter-0")
     real = ScratchRealization(realdir)
 
-    eclfiles = real.get_eclfiles()
-    assert isinstance(eclfiles, ecl2df.EclFiles)
-    compdat_df = ecl2df.compdat.df(eclfiles)
+    resdatafiles = real.get_resdatafiles()
+    assert isinstance(resdatafiles, res2df.ResdataFiles)
+    compdat_df = res2df.compdat.df(resdatafiles)
     assert not compdat_df.empty
     assert "KH" in compdat_df
 
 
 def test_reek():
-    """Import the reek ensemble and apply ecl2df functions on
+    """Import the reek ensemble and apply res2df functions on
     the realizations"""
 
     if "__file__" in globals():
@@ -48,19 +48,19 @@ def test_reek():
     reekens = ScratchEnsemble(
         "reektest", testdir + "/data/testensemble-reek001/" + "realization-*/iter-0"
     )
-    if not HAVE_ECL2DF:
+    if not HAVE_RES2DF:
         pytest.skip()
 
     def extract_compdat(kwargs):
-        """Callback fnction to extract compdata data using ecl2df
+        """Callback fnction to extract compdata data using res2df
         on a ScratchRealization"""
-        eclfiles = kwargs["realization"].get_eclfiles()
-        if not eclfiles:
+        resdatafiles = kwargs["realization"].get_resdatafiles()
+        if not resdatafiles:
             print(
-                "Could not obtain EclFiles object for realization "
+                "Could not obtain ResdataFiles object for realization "
                 + str(kwargs["realization"].index)
             )
-        return ecl2df.compdat.deck2dfs(eclfiles.get_ecldeck())["COMPDAT"]
+        return res2df.compdat.deck2dfs(resdatafiles.get_deck())["COMPDAT"]
 
     allcompdats = reekens.apply(extract_compdat)
     assert not allcompdats.empty
@@ -69,16 +69,18 @@ def extract_compdat(kwargs):
     # Pr. now, only realization-0 has eclipse/include in git
 
 
-def test_smry_via_ecl2df():
-    """Test that we could use ecl2df for smry extraction instead
+def test_smry_via_res2df():
+    """Test that we could use res2df for smry extraction instead
     of the native code inside fmu-ensemble"""
 
     def get_smry(kwargs):
-        """Callback function to extract smry data using ecl2df on a
+        """Callback function to extract smry data using res2df on a
         ScratchRealization"""
-        eclfiles = kwargs["realization"].get_eclfiles()
-        return ecl2df.summary.df(
-            eclfiles, time_index=kwargs["time_index"], column_keys=kwargs["column_keys"]
+        resdatafiles = kwargs["realization"].get_resdatafiles()
+        return res2df.summary.df(
+            resdatafiles,
+            time_index=kwargs["time_index"],
+            column_keys=kwargs["column_keys"],
         )
 
     if "__file__" in globals():
@@ -89,7 +91,7 @@ def get_smry(kwargs):
     reekens = ScratchEnsemble(
         "reektest", testdir + "/data/testensemble-reek001/" + "realization-*/iter-0"
     )
-    if not HAVE_ECL2DF:
+    if not HAVE_RES2DF:
         pytest.skip()
 
     callback_smry = reekens.apply(get_smry, column_keys="FOPT", time_index="yearly")
@@ -97,4 +99,4 @@ def get_smry(kwargs):
 
     assert callback_smry["FOPT"].sum() == direct_smry["FOPT"].sum()
     assert callback_smry["REAL"].sum() == direct_smry["REAL"].sum()
-    # BUG in ecl2df, dates are missing!!
+    # BUG in res2df, dates are missing!!
diff --git a/tests/test_util.py b/tests/test_util.py
index c0e9e72d..e45a45d2 100644
--- a/tests/test_util.py
+++ b/tests/test_util.py
@@ -1,4 +1,5 @@
 """Test general utility functions in use by fmu.ensemble"""
+
 import datetime
 import logging
 
diff --git a/tests/test_virtualrealization.py b/tests/test_virtualrealization.py
index 1acf6d66..41a9c5b2 100644
--- a/tests/test_virtualrealization.py
+++ b/tests/test_virtualrealization.py
@@ -1,4 +1,5 @@
 """Testing fmu-ensemble, virtual realizations"""
+
 # pylint: disable=protected-access,duplicate-code
 
 import datetime