This modeling study addresses the question, whether HCCI piston engines can be used as chemical reactors in a polygeneration process. In this context, a combustion engine is used to produce hydrogen by partial oxidation in the engine and the further auxiliary units assure the purification of hydrogen. Several aspects were addressed during the development of the process regarding fresh-gas- and exhaust gas-treatment and energy integration. The fresh gas preheating for methane ignition was achieved by recirculation of hot exhaust gas, which also contributed to a high flexibility towards power-, heat- and hydrogen-output. Exergetic efficiencies, process-outputs and fuel consumption were calculated and compared for different operation points. Exergetic efficiencies of up to 80% were achievable and this high efficiency leads to reduced fuel consumption, with up to 40% fuel savings compared to the separated production of power, heat and hydrogen. Power and heat flow of the process can be adjusted very flexibly and the ratio can be varied within a factor of two within the investigated operating conditions. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.