Brazil has great energy potential for the production of biodiesel, due to its great size and variety of climates with many regions of pastures and because it is one of the greatest exporters of bovine meat of the world. Beef tallow is a potential raw material for the production of biodiesel, presenting an efficient transesterification and easy separation of phases. In this work, the transesterification of the tallow by homogeneous catalysis with a solution of methanolic of KOH was carried out by means of heating and preliminary formation of a microemulsion. In this study, the biodiesel obtained was characterized by physicochemical means of the Norms of the ANP 07/2008. Fatty acids from beef tallow were characterized by gas chromatography−mass spectrometry (GC−MS) and quantified by thermogravimetric analyses (TGA). Similar quantities of saturated and unsaturated fatty acids were observed by correlation GC−TGA. The beef tallow biodiesel obtained using a simple methodology presented a high yield (96.26%), even though the raw material had high quantities of FFA (3.6 ± 0.02%).