Methyl esters and glycerol are the products of transesterification reaction of any oil or fat. Thus, after the separation of glycerol from biodiesels produced from two types of spent frying oils, namely, spent cooking oil and spent fish frying oil, the produced methyl esters were purified using the activated carbon and surface modified activated carbons to assess the ability of these adsorbents on providing satisfied yields and accepted properties of the produced fuels in comparison to the water washing method. Properties of the produced fuels including the density, kinematic viscosity, acid value, refractive index, pour point, flash point, and higher heating value were measured. The study disclosed that, regardless the type of the activated carbon, the use of activated carbon for biodiesel purification results in higher yield and better properties as compared to those purified by the water washing method. Moreover, properties met the standard limits according to the ASTM standards.