A study is conducted on a cogeneration system that incorporates a natural gas fed internal-reforming solid oxide fuel cell (IRSOFC) and a zeolite/water adsorption chiller (AC). The main aim is to investigate the performance of this combined system under different operating conditions and design parameters. A mathematical model is developed to simulate the combined system under steady-state conditions. The effects of fuel flow rate, fuel utilization factor, circulation ratio, mass of adsorbent and inlet air temperature on the performance are considered. The results show that the proposed IRSOFC-AC cogeneration system can achieve a total efficiency (combined electrical power and cooling power) of more than 77%. The electrical efficiency is found to decrease as the fuel flow rate increases, while the cooling power increases to a constant value. The total efficiency reaches a maximum value with variation of the fuel utilization factor. Both the circulation ratio and the inlet air temperature exert positive impacts on system efficiency. (c) 2005 Elsevier B.V. All rights reserved.