In this work, a lumped kinetic model for the hydrocracking of vacuum residue (VR) from Maya crude oil was developed. A preliminary kinetic analysis based on the conversion of VR was performed. Next, ten models with increasing level of complexity were proposed and solved sequentially using Matlab (R) software. All models included four lumps: products with boiling point >450 degrees C (L+), products with boiling point <450 degrees C (L-), gas and coke. Kinetic parameters were estimated from the experimental data obtained in a microbomb batch reactor at three temperatures (400, 425 and 450 degrees C) and four holding times (10, 30, 60 and 90 min). Two catalysts, NiMo/Al2O3 and NiMo/Al2O3-Cr (alumina doped with chromium), were tested. Kinetic results showed that gas was mainly produced from the decomposition of L- at low temperatures, whereas at 450 degrees C gas is predominantly formed from cracking of L+. Moreover, coke was found to be exclusively produced from L+ at all temperatures. In general, NiMo/Al2O3 gave rise to higher yields of L- than NiMo/Al2O3-Cr. Nevertheless, NiMo/Al2O3-Cr was able to retain greater activity at higher temperatures. (C) 2013 Elsevier Ltd. All rights reserved.