Biomass derived fuels are preferred as alternate fuels for I.C Engines due to their abundant availability and renewable nature. Fuels such as methanol and ethanol have proved to be suitable alternate fuels in the transport sector. In the present work the performance, emission and combustion characteristics of a single cylinder, constant speed, direct injection diesel engine using orange oil as an alternate fuel were studied and the results are compared with the standard diesel fuel operation. Results indicated that the brake thermal efficiency was higher compared to diesel throughout the load spectra. Carbon monoxide (CO) and hydrocarbon (HC) emissions were lower and oxides of nitrogen (NO(x)) were higher compared to diesel operation. Peak pressure and heat release rate were found to be higher for orange oil compared to diesel fuel operation. (C) 2008 Elsevier Ltd. All rights reserved.