[en] Full text: There is a worldwide trend in a search for renewable materials for the production of fuels and chemicals, in order to reduce dependence on fossil fuels and the level of atmospheric CO₂ . Among these materials, clay minerals outcome due to their abundance in nature and reuse possibility. Meanwhile, studies from SILVA (2008), demonstrated that the clay materials after chemical modifications have significant catalytic activity. This study aims to evaluate the catalytic performance of attapulgite clay mineral after the incorporation of aluminum and molybdenum to use the new catalysts in the transesterification reactions of the cotton and soybean oils. The incorporation of aluminum was carried out by dripping at a speed of 1.5 ml/min of sodium hydroxide in an aluminum chloride solution, both at a concentration of 0.2 mol/L under continuous stirring. After this period, the solution was aged for 24 hours, and then the solid was separated by vacuum filtration. The impregnation of molybdenum on the clay after incorporation of aluminum was performed by physical dispersion using 5% of the metal. The chemically modified catalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and Fourier transform infrared spectroscopy (FTIR). The reaction was conducted in an autoclave reactor with heating at 200°C, using 1/12 oil/alcohol molar ratio and 5% of the catalyst. After testing, the products were characterized by gas chromatography and the kinematic viscosity. The catalytic performance of the aluminum modified material was about 20% conversion for both oils, while the incorporated and impregnated catalyst achieved a conversion of 30% for both oils. Reference: [1] SILVA, A. A.Novos catalisadores a base de argilas para a produção do Biodiesel, 167p. Tese.UFCG,Campina Grande-PB,2008. (author)