Biodiesel production is a very hot issue within research, politics and investments worldwide. Thernproblem of finding economically viable and environmentally friendly renewable energy sourcesrnis an urgent matter. Not only is the world faced with a finite supply of fossil-fuels, but concern isrngrowing over the possibility of climate change caused by greenhouse gas emissions. Biodiesel, arnliquid fuel derived from plant oils or animal fats, represents a renewable energy source that couldrncontribute to the solution of both problems; it can be continually produced as long as we are ablernto grow plants and it can be made in such a way as to release no net addition of greenhouse gasesrnto the environment. However, technical challenges must be overcome before biodiesel canrncontribute significantly to the world's energy supply; with current technology biodieselrnproduction is profitable only under special circumstances.rnThis thesis research seeks to address this problem by studying the production of biodiesel usingrnheterogeneous catalysts. Heterogeneous catalysts can make biodiesel more energy efficient, andrntherefore less expensive, by eliminating the need for expensive purification processes thatrnseparate the catalyst from reaction products typical in the use of homogeneous catalysts. Thernexperimental design and statistical analysis was done by Design-Expert 7.0.0 program. Fatty acidrnmethyl ester was produced via transesterification process using sodium phosphate as arnheterogeneous catalyst and purified jatropha curcas oil which is extracted from the jatropha seedrnbought from dessie. To obtain a high quality biodiesel fuel that comply the specification ofrnstandard methods, some important variables such as reaction temperature, molar ratio ofrnmethanol to oil and mass weight of catalyst were selected and studied. At the followingrnconditions; 333K of reaction temperature, methanol to jatropha oil ratio of 4 and 5 mass wt% ofrncatalyst, an optimum fatty acid methyl ester yield of 94.98% was obtained, indicating thatrnsodium phosphate has the potential as a heterogeneous catalyst for the production of fatty acidrnmethyl ester from jatropha oil. Moreover, physico-chemical characterization of the fatty acidrnmethyl ester was performed and compared with the standard biodiesel properties.