An experiment is to be carried out in a single cylinder, four stroke, air cooled, direct injection diesel engine by using diesel fuel, cotton seed oil methyl ester (csome), blends of diesel and CSOME in proportions of 20%/80%, 40%/60%, 60%/40%, 80%/20%, 50%/50% by volume. Cotton seed biodiesel has good oxidation stability, but poor low temperature properties. The performance, combustion and emission characteristics of CSOME, blends of diesel and CSOME are to be compared with the result obtained from the baseline diesel fuel.