From June 1993 until May 1994 a fully automatic fuel cell-combined heat and power station of the type PC25 with 200 kW electric output provided with fuel cells of the phosphorous-acidic type was tested by the Hessian Utility Joint-Stock Company. Since then the combined heat and power station has been operated under normal conditions. A scientifically accompanying programme attended to the measuring of emissions and the investigation of the gas process engineering. The concentration of carbon monoxide, hydrocarbons and nitrogen oxides in the waste gases of the fuel cell and the gas composition at the most important points of the gas processor were measured and recorded on-line.