This paper presents the performance results of a 5.9 kW stationary diesel engine which was converted into spark ignition mode and run on compressed natural gas (CNG), methane enriched biogas (Bio-CNG) and biogas produced from biomethanation of jatropha and pongamia oil seed cakes. The performance of the engine with 12.65 compression ratio was evaluated at 30 degrees, 35 degrees and 40 degrees ignition advance of TDC. The maximum brake power produced by the engine was found at ignition advance of 35 degrees TDC for all the tested fuels. In comparison to diesel as original fuel, the power deteriorations of the engine was observed to be 31.8%, 35.6% and 46.3% on compressed natural gas, methane enriched biogas and raw biogas, respectively, due to its conversion from CI to SI mode. The methane enriched biogas showed almost similar engine performance as compared to compressed natural gas in terms of brake power output, specific gas consumption and thermal efficiency. (C) 2011 Elsevier Ltd. All rights reserved.