There is a need to find suitable substitutes for the petroleum based fuels as the conventional fuels are decreasing in order in recent years. Vegetable oils are attractive as an alternative fuel for diesel engines as they are renewable and can be used in engines without employing any major modifications. The main problems with the use of neat vegetable oils in diesel engines are high smoke levels and relatively low thermal efficiency due to high viscosity and carbon residue as compared to diesel. In this work various methods for improving the performance of rubber seed oil (RSO) fuelled diesel engine are compared and discussed. Dual fuel operation with hydrogen, ethanol and DEE resulted in higher brake thermal efficiency. Oxides of nitrogen (NOx) level are lowest with neat RSO engine operation. It increases about 36% for dual fuel operation with hydrogen and 32% with DEE injection compared to neat RSO. Smoke emission reduces from 6.1 Bosch Smoke Unit (BSU) for neat RSO operation to 3.8 BSU for hydrogen induction, 4 BSU for DEE injection and 3.4 BSU for ethanol injection which is the lowest value compared to all other test fuels. Peak pressure and rate of pressure rise are higher for all the methods as compared to neat RSO operation. Ignition delay is higher for neat RSO operation; it further increases with dual fuel operation with hydrogen, LPG and ethanol. It is concluded that dual fuel operation with hydrogen and DEE is effective in improving the performance of neat rubber seed oil in compression ignition engine operation.