A major hurdle in commercialization of biodiesel from vegetable oil, in comparison to petroleum-based diesel fuel, is its cost of manufacturing, primarily the raw material cost. Waste cooking oil is one of the economical sources for biodiesel production. NaOH and KOH catalyzed processes for prepared of biodiesel expressed of fatty acid methyl ester were comparatively studied for refined sunflower (Helianthus annuus L) oil and waste cooking oil. Transesterification was carried out using 100% excess methanol; i.e. molar ratio of methanol to oil is 6:1 and catalyst concentration of 0.5% at 60 o C. Fuel properties and specifications such as viscosity, flash point, cloud point, pour point, density, cetane number, and acidic value are determined and compared to each other and petroleum diesel. This study characterizes the fuel properties of biodiesel produced from refined sunflower oil and waste cooking oil using two different catalysts (NaOH and KOH) to provide a comprehensive understanding of biodiesels.