Methyl esters from various vegetable oils have been increasingly used in diesel engines to partially substitute or replace petroleum fuels. In this present study biodiesel was produced from sunflower oil by base-catalyzed transesterification process. A 30 L per batch experimental installation was used to produce biodiesel using a molar ratio of alcohol to oil 6:1, a reaction temperature of 65 °C and a reaction time of 2 hours. A characterization and quality evaluation were done by measuring viscosity, flash point, density, fatty acid compositions, elementary and thermal analysis of sunflower oil, sunflower oil biodiesel and petroleum fuel. The results show poor atomization due to the high viscosity with the increase of combustion chamber deposits. Biodiesel has less carbon and hydrogen content than diesel fuel. The process of volatilization for sunflower oil biodiesel initiates and finishes in temperatures that are much higher than diesel.