In the present scenario, world energy consumption is increasing rapidly every year because of the increasing trend of modernization and industrialization. Crude oil is the major source for producing energy, results in the degradation of the environment due to fossil fuel combustion. Moreover, the combustion products like carbon di-oxide (CO2), sulphur di-oxide (SO2), and nitrogen oxide (NOx) causes global warming. Crude oil depletes every year, to satisfy the energy demands, the crude oil is imported. The environmental problems caused by the indiscriminate use and scarcity of petroleum are the major factor to explore renewable energy resources. The idea of vegetable oil as a fuel to run diesel engines has been on the world stage over a century ago. Vegetable oil is an alternative fuel as a source of energy has been receiving great attention among the researchers because of its renewability, biodegradability, non-toxic and better quality of exhaust gas emissions. A lot of edible and inedible vegetable oils which can be exploited for substitute fuel as diesel fuel, i.e., jatropha, karanja, rubber seed, cottonseed, palm oil, sun flower oil, rape seed oiland neemoils etc., has been selected and discussed the performance, combustion and emission characteristics of diesel engine under the various working conditions.