The present work is aimed at exploring the performance characteristics of a gas engine heat pump (GEHP) system in the aspect of the heating and domestic hot water. A test prototype was established using R134a as working fluid. The performance characteristics of the gas engine and the GEHP system working were studied by experiments in heating mode. The results showed that the output efficiency of the gas engine increased when the gas engine speed is constant. The coefficient of performance (COP) and primary energy ratio (PER) of the GEHP system decreased with the growing of the gas engine speed, but increased with increasing condenser water inlet temperature and ambient air temperature. And the PER of the GEHP system was between 1.23 and 1.48 under experimental condition. In addition, the energy of heat recovery accounted for about 30%-45% of the total heating capacity of the GEHP system, and the temperature of the domestic hot water which was heated by the waste heat could reach 40 degrees C-60 degrees C, thus ordinary families' demands for domestic hot water could be satisfied. (C) 2017 Elsevier B.V. All rights reserved.