Used vegetable oils in frying processes constitute a waste that, if not managed correctly, results in environmental damage and deterioration of human health. When used as raw material in the preparation of biofuels, the oil has to purify. The aim of this research was to study the purification process of used cooking oil using natural zeolite as an absorbent material. The physicochemical properties of the oil used were determined. Zeolite was analyzed using X-ray diffraction, Raman Spectroscopy and Scanning Electron Microscopy. A multilevel factorial experimental design was planned for the first adsorption stage. The operational variables investigated were temperature (80, 100, 120 ℃), particle diameter (0.315, 0.630, 1 mm), and zeolite ratio (m/m) (5, 10%). The osrder of the reaction was determined from the kinetic study. It was concluded that, to obtain minimum absorbance values, which imply greater impurity removal, it is necessary to work at low temperatures, with smaller particle diameters and a higher proportion of zeolite. For a second absorption stage, varying the proportion of zeolite showed a decrease in absorbance values. Homogeneous transesterification reactions, with both, unpurified and purified oil in two stages had performed and a higher yield with the purified oil was obtained.