Sensitivity analysis is an important tool commonly used for confirming the achievement of the optimum set of parameter values obtained by regression analysis. To highlight this importance, two cases reported in the literature for the kinetic modeling of hydrocracking of heavy oils were selected, and sensitivity analysis was performed for the reported parameters. It was found that the values of the reported kinetic parameters do not reach the minimization of the objective function based on the sum of squares errors between predicted and experimental product yields, so that the reported set of kinetic parameters is not the optimal one. The calculated optimized reaction rate coefficients fitted better to experimental data than those reported in the literature. It was demonstrated that sensitivity analysis is of great relevance for determining the best set of parameters, and thus establishing proper reaction pathways, values of reaction rate coefficients, and activation energies, whereby reactor modeling, simulation, design and optimization can be done in an effective manner.