This paper presents a methodology for effective control of fuel cell devices connected to an electric utility distribution network. A controller is developed for a fuel cell power plant to assist the conventional generators to damp out oscillations, which is possible by utilizing the fast response characteristic of fuel cells. It achieves the objective by generating appropriate switching signals to the DC-AC inverters and modulating both active and reactive powers. Computer model of the controller is developed and its effectiveness is proved by a sample test. Fuel cell devices, therefore, can be used to improve power system stability when these are applied to a power distribution system. (C) 2002 Elsevier Science Ltd. All rights reserved.