In this present work experimental test have been conducted to evaluate the performance and emission characteristics of a diesel engine using the rubber seed oil diesel
blends. The properties of neat rubber seed oil like viscosity, volatility and the boiling point are higher than diesel; the rubber seed oil has a lesser cetane number than diesel which prevented the 100% replacement of diesel with the rubber seed oil in the diesel engines. In the present work, rubber seed oil and its blends with petroleum based diesel were tested as a fuel in the diesel engine. The blends were prepared in the proportion of 25%, 50% and 75% rubber seed oil with diesel fuel.