A large amount of waste cooking oil is generated by the restaurants in Hong Kong every day. Currently, there is no efficient way to dispose of this waste material, which are simply dumped into sewers. In 1997, the government collected about $220M as sewage charges from the restaurant trade. This poses a heavy burden on the trade as well as on the government's wastewater treatment facilities. Biodiesel is a clean-burning fuel made from natural, renewable sources such as vegetable oils. The study on the feasibility of replacing diesel by biodiesel fuel is increasing in recent years due to the increasing pressure in reducing the emissions from diesel vehicles. Biodiesel is considered as a cleaner alternate fuel to substitute the diesel fuel in USA and many other countries in Europe. This paper presents our study on the biodiesel production technology using waste cooking oil generated from local restaurants. Different recipes to make biodiesel from waste oil are investigated and compared with those produced from neat vegetable oil. The effect of process parameters, such as mixing, reaction and washing times, heating temperature for filtration and separation, reaction temperature, incoming feedstock quality etc. on the quality of biodiesel produced will be discussed based on the preliminary data obtained.