This paper presents the guidelines for simulation of fuel-cell (FC) stacks by using a computer-controlled high-power converter, which drives actual electric loads, or injects power to the grid. The FC output static And dynamic characteristics are closely reproduced in such a way the actual loads are seamlessly driven as if they were supplied by the simulated FC. The simulator characteristics include the membrane temperature and humidity, efficiency, flow of the reactants, cooling air fan and water pumps, the actual air environmental temperature and humidity, and the regimen of operation of the. actual electrical load. Any type of FC of ordinary size can be simulated without having to use hydrogen with improved safety, variety of tests, flexibility, and demo facilities. Those features allied to the low cost of this FC simulator contribute for market Analysis And life-cycle studies of a site installation.