Biodiesel is an alternative fuel that is cleaner than petrodiesel. Biodiesel can be used directly as fuel for a diesel engine without having to modify the engine system. It has the major advantages of having high biodegradability, excellent lubricity and no sulfur content. This paper presents the results of investigations carried out in studying the fuel properties of soybean methyl ester (SME) and its blend with marine diesel fuel from 5%, 20% and 50% blends by volume and in running a diesel engine with these fuels. The results indicate that the use of biodiesel produces lower smoke opacity (up to 74%), but higher brake specific fuel consumption (BSFC) (up to 12%) compared to marine fuel (MF). The measured carbon monoxide (CO) emissions of B5 and B100 fuels were found to be 3% and 52% lower than that of the MF, respectively. (C) 2011 Elsevier Ltd. All rights reserved.