A Maya residuum was reacted in a perfectly mixed reactor in continuous operation under hydrogen in the presence of a hydrotreating commercial catalyst supported on gamma-Al2O3 at 12.5 MPa of hydrogen pressure, at different temperatures (375, 400, and 415 degrees C), and at different mass space velocities (between 1.4 and 7.1 L/h.g(cat)). The reaction products were separated into fractions with different boiling points and a kinetic scheme involving lumped species consisting of the fraction over the 343 degrees C boiling point (atmospheric residuum), that below the 343 degrees C boiling point (light oils), and gases has been proposed. Experimental data at 375 and 400 degrees C have found a good fit to the model but not at 415 degrees C. The percent conversion of sulfur, nitrogen, vanadium, and nickel and the average molecular weight reduction have been analyzed as a function of atmospheric residuum conversion. The number or moles or carbon-carbon bonds broken by reaction has also been estimated.