In the scenario of energy crisis, the question of alternative fuel comes to meet our current energy demand. Jatropha oil and Castor oil can be an important alternative fuel to substitute petroleum fuel to some extent. But the high viscosity of these oils limited their use as fuel. This paper aims at the solution of the problem by encouraging the use of Jatropha and Cator oil. Attempt is made to reduce viscosity of Castor oil by using mixture of oil which does not work significantly. Chemical treatment with H2S, NaOH and H2SO4 are made but among these H2S reduces viscosity from 153.36 cSt to 129.2 cSt at 400C and burning period increases from 8 minutes to 15 minutes.