Biodiesel is a biodegradable and alternative fuel to petroleum diesel. The methyl esters are produced from transesterification of vegetable oils or animal fats with alcohol in the presence of an acid or a basic catalyst.. In this work, biodiesel was obtained by a transesterification reaction of bovine fat with methanol using KOH as a catalyst. The raw material and the biodiesel were characterized by their composition in fatty acids. Blends of diesel/biodiesel were produced in several concentrations and were assessed in relation to some combustible properties, according to the ASTM standards. The blends diesel/biodiesel and biodiesel (B100) were also compared with diesel through consumption tests, in a diesel engine used for energy generation. All tests demonstrated that biodiesel and its formulations with diesel can present similar results, or sometimes better results, to those of mineral diesel.