This work reports on the performance of a 3 kWe proton exchange membrane fuel cell under a range of loads as well as a thermodynamic analysis of the results. A test bench was constructed and used to evaluate the performance of fuel cells. It was found that gross first law efficiencies of over 48 percent and second law efficiencies of over 55 percent were achieved. The gross work calculated from a first law analysis using measured parameters averaged within 3 percent of the directly measured gross electrical output for the four power levels tested.