diff --git a/cadbiom_cmd.py b/cadbiom_cmd.py
index 40a2d0016b0adb2fd2347011e435fa09eb6e0b67..4bb78dda6632b20f10ec885cb288543db467c6c0 100644
--- a/cadbiom_cmd.py
+++ b/cadbiom_cmd.py
@@ -43,6 +43,8 @@ def launch_sort(args):
 def parse_trajectories(args):
     """Parse a complete solution file and make a representation of trajectories.
 
+    The output is in graphml file format and is exported in 'graphs' directory.
+
     .. note:: Requires the model file.
     """
 
diff --git a/graphs/.gitignore b/graphs/.gitignore
new file mode 100644
index 0000000000000000000000000000000000000000..d6b7ef32c8478a48c3994dcadc86837f4371184d
--- /dev/null
+++ b/graphs/.gitignore
@@ -0,0 +1,2 @@
+*
+!.gitignore