A 50 kW PEMFC pilot plant has been operated 4400 h using hydrogen originating from a sodium chlorate production process after standard industry purification processes were applied. The first stage of the fuel cell system operation was performed using anode gas recirculation, while in the other stages an open anode configuration was applied. The fuel cell system did not show extensive degradation despite the low quality of the hydrogen and frequent shut-downs. The average degradation rate was 2-3 mu V per hour at low and medium currents (10-150 A). The main causes for any unreliability were found to be hydrogen supply side system components, namely pressure reducers and valves. Recommendations are given for the improvement of both PEMFC power plant design and operation for industrial hydrogen applications. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.