This work throws light on the following aspects: 1.Abstract 2.Introduction to the problem and problem statement 3.Global Energy Scenario 4.Indian Energy Scenario 5.Bio-Diesel as good alternative 6.Benefits of bio-Diesel 7.Production Process of Bio-Diesel 8.Cotton and Fish oil as potential Bio-Diesels. 10.Biology,agricultural aspects of cotton & fish oil 11.Performance characteristics 12.Combustion Characteristics 13.Emission Characteristics 14.conclusive statements based on the technical data obtained from running the engine on cotton and fish oil Bio-Diesels.