The sulfuric acid leaching of zinc plant residues was studied in an attempt to find a suitable hydrometallurgical method for zinc recovery. The parameters evaluated consist of reaction time, Solid-to-liquid-ratio, reaction temperature, agitation rate and pH. The results of kinetic analysis of the leaching data under various experimental conditions indicated that there is a reaction controlled by the solution transport of protons through the porous product layer with activation energy of about 1 kJ/mol for different constant solid to liquid ratios. Based on the shrinking core model (SCM), the following semiempirical rate equation was established:1-3(1-a)2/3+2(1-a)=0.001187×[H⁺]^0.016×[(S/L)]^-1.34×exp(-1/RT) ×t. On the other hand, activation energy was obtained from a model-free method using isothermal measurements. Values for activation energy were calculated as a result of the conversion function with an average of 2.9 kJ/mol. This value is close to that determined previously, using shrinking core model (SCM).