Biofuel has so far been backed by government policies in the quest for low carbon fuel in the near future and promises to ensure energy security through partially replacing fossil fuels. At present biodiesel is mostly produced by transesterification reaction from oil-seed feedstock and has to conform to ASTM D6751 specifications. Biodiesel sustainability has sparked debate on the pros and cons of biodiesel and the question of food security. The use of waste cooking oil such as palm and coconut oil in diesel engines is more sustainable if they can perform similarly to ordinary diesel fuel (B0). This paper presents the experimental study carried out to evaluate emission and performance characteristics of a multi-cylinder diesel engine operating on waste cooking oil such as 5% palm oil with 95% ordinary diesel fuel (P5) and 5% coconut oil with 95% ordinary diesel fuel (C5). B0 was used for comparison purposes. The results show that there are reductions in brake power of 1.2% and 0.7% for P5 and C5 respectively compared with B0. In addition, reduction of exhaust emissions such as unburned hydrocarbon (HC), smoke, carbon mono-oxide (CO), and nitrogen oxides (NOx) is offered by the blended fuels. (C) 2010 Elsevier Ltd. All rights reserved.