An h-adaptive mesh procedure to solve the reaction-diffusion problem for multiple reactions in catalytic pellets presenting strong diffusion limitations is developed. The discretization approach selected for this purpose is based on an integral formulation of the conservation equations. The adaptive mesh procedure relies on estimating the error of local reaction rate evaluations. By adding or removing nodes the errors will eventually become bounded within pre-set limits. The algorithm is tried on some test cases derived from the liquid phase catalytic hydrogenation of butadiene and butyne in butene (1, 2-cis and 2-trans) rich hydrocarbon mixtures.