The potential of biodiesel generation from RCO is evaluate dusing the case of Singapore. Data are collected in questionnaire/interview surveys to better understand the barriers and challenges of wide scale biodiesel production. The generation rates of RCO from cooking oils are estimated from the surveys and used to infer the replacement rate of biodiesel for fossil diesel demand. Inaddition, surveys designed for the RCO processors and commercial vehicles fleet owners provide details on the barriers/challenges that need to be bridged to facilitate a viable biodiesel implementation in a city.Singapore can adopt biodiesel to a greater extent in the bid to reduce GHGs to mitigate climate change. Agricultural land isscarce; hence, making biodiesel produced from food crops unsuit-able as a mitigation measure. Biodiesel production via sources of biomass wastes such as animal fats and plant cellulose materials requires import of raw stocks for processing and is thus unattractive and ineffective for climate change mitigation. On the other hand,a heavily populated city consumes and generates plenty of food wastes which include spent cooking oil that can be feedstock for biodiesel