The aim of present study is to examine the dissolution and kinetics of valuable metals from spent hydrodesulfurization catalyst using potassium hydroxide. Due to low solubility of metal oxides of Ni and Co in alkali medium, only the recovery of Mo and Al was investigated. Optimum roasting temperature and time were determined 600?C and 60 min., respectively. The maximum dissolution yields of Mo (83.54%) and Al (36.89%) were reached under optimum leaching conditions. The leaching behavior of both metals is represented by the shrinking core model and liquid film diffusion is controlled the process. Activation energies found to be 14.71 kJ/mol and 17.84 kJ/mol for Mo and Al, respectively.