Globalization, urbanization and industrialization showed the way for production, manufacturing activities and competition which eventually resulted in proliferation of prices, population, emissions and scantiness of petroleum resources which lead the researchers to scrutinize alternative fuels for diesel engines thusly becoming a hot topic in society and government. Owing to the failure in decreasing the emissions and increasing the efficiency, industries and researchers are being attracted towards biodiesels which endeavors sound assurance of solving major energy problems. Biodiesel is an alternative, renewable, biodegradable fuel having environmental benefits ranging from minimizing global warming pollution to decreasing the countries dependence on oil to pushing economical, sustainable and smart growth. Biodiesels are the mono alkyl esters of vegetable oils or animal fats which are produced domestically from a triglyceride feedstock by trans esterifying it with methanol or various short-chain alcohol. In this paper, the research efforts are directed towards improving the performance of C.I. engine using ethyl ester Kusum oil (Vegetable oil) and its blends with diesel as a fuel. The performance of a single-cylinder, four stroke, C.I. engine was studied using Kusum oil ethyl ester and its blends with diesel with the engine being operated at various loading conditions with water cooling system. Engine performance (brake power(bp), brake specific fuel consumption(bsfc), brake specific energy consumption and brake thermal efficiency(?)) and emissions (CO, HC, NOx and smoke opacity) were measured to analyze the behavior of the diesel engine running on biodiesel.