Ansaldo Fuel Cells, SpA
Astris Energi, Inc.
Ballard Power Systems, Inc.
Dais-Analytic Corporation
Delphi Corporation (formerly Delphi Automotive Systems)

FuelCell Energy, Inc. (includes solid oxide fuel cell operations formerly developed by Global Thermoelectric, Inc.)

Fuel Cell Technologies Corporation
Hydrogenics Corporation
IdaTech, LLC 
Nuvera Fuel Cells, Inc.
Plug Power, Inc.

Proton Energy Systems, Inc. -- subsidiary of Distributed Energy Systems Corporation

ReliOn, Inc. (formerly Avista Laboratories, Inc.)
Siemens Westinghouse Power Corporation
SOFCo-EFS Holdings, LLC -- subsidiary of BWX Technologies, Inc.
Sulzer Hexis, Ltd.
UTC Fuel Cells (formerly International Fuel Cells (IFC)/ONSI)
ZTEK Corporation