Mathematical models for the mechanical properties of a CoMoP/Al2O3 hydrotreating catalyst in the sulfidation process are developed with response surface methodology. A Doehlert design is performed to collectively study the effects of sulfidation temperature, time and heating rate on the mean strength, Weibull modulus and pellet density. Analysis of variance reveals that the models developed for the mean strength and Weibull modulus are adequate. The validity of the models is also verified by experimental data. Analyses of response surfaces show that in the great part of the experimental domain examined. as the sulfidation temperature increases the mean strength decreases, while the Weibull modulus increases at first and then decreases. The middle level of the sulfidation time results in smaller mean strength and higher Weibull modulus. The Weibull modulus decreases with increasing heating rate: however. the effect of the heating rate on the mean strength is statistically less pronounced. It is concluded that there is a great potential for improving the catalyst mechanical reliability in the sulfidation process, while the pellet density does not vary significantly. (C) 2008 Elsevier Ltd. All rights reserved.