The International Patent Classification (IPC) classifies fuel cells under H01M, which includes batteries for the direct conversion of chemical into electrical energy. Methods relating to the manufacturing of fuel cells are found under H01M8 and its subclasses. Fuel cells installed in vehicles can be found under B60K.
In the Cooperative Patent Classification (CPC), which is based on the IPC and used by about two dozen patent offices, fuel cells are classified under H01M. Fuel cells installed in vehicles can be found under B60K.