The primary problems associated with the use of pure vegetable oils as fuels in compression ignition (Diesel) engines are caused by high fuel viscosity. Transesterification of the oil with short-chain alcohols (such as methanol or ethanol) to corresponding fatty esters is the most promising solution to the high-viscosity problem. In this work, the transesterification method was applied to crude safflower seed oil of Turkish origin using methanol. The variables affecting the monoester yield, such as : 1. Molar ratio of alcohol to vegetable oil; 2. Reaction temperature; and 3. Type and amount of alkali catalyst used were investigated. In the presence of 1.0 wt% KOH as the reaction catalyst, 97.7% ester yield was achieved within 18 min at a reaction temperature of 69 +/- 1 degrees C using 1:7 vegetable oil-alcohol molar ratio. A significant improvement was observed in viscosity and other physical properties with the ester product compared to the parent vegetable oil. ASTM fuel properties of the methyl ester product were in accordance with those obtained for commercial Grade No.2-D diesel fuel.