Biodiesel is proved to be the best replacement for diesel because of its unique properties like significant reduction in green house gas emissions, non-sulfur emissions, non-particulate matter pollutants, low toxicity and biodegradability. This paper reviews the pretreatment step, the physical and chemical properties of waste cooking oil, etherification, transesterification and production of biodiesel from waste cooking oil by various methods. and catalysts reported so far. The factors affecting the process parameters reported are studied and the point of interest focuses on their alcohol to oil ratio, reaction temperature, catalyst both qualitative and quantitative scope. The optimum condition is investigated and the exhaust emissions of biodiesel and petroleum diesel are compared.