Abstract: This study is an investigation on fast pyrolysis technology of oil palm empty fruit bunches (EFB) to bio-oil. EFB is one of the solid wastes that are rapidly increasing in the palm oil industry. The composition and particle size distribution of the unwashed feedstock and washed feedstock were determined and its thermal degradation behaviour was analysed by thermogravimetric analysis (TGA). A 150 g/h fluidized bed bench scale fast pyrolysis unit was used to study the impact of key variables: reactor temperature in the range of 425°C to 550°C and feedstock ash content in the range of 1.15 to 5.43 mf wt%. The properties of the liquid product were analysed and compared with wood derived bio-oil and petroleum fuels. It was found that the maximum ash content of washed feedstock that produced homogenous liquids is less than 3 mf wt%. The results of pyrolysis experiments showed that the bio-oil from washed EFB with low ash content had similar properties as...