This work is a continuation of studies related to the kinetics of dissolution of oxides and hydroxides of aluminum (III) and chromium (III). Earlier studies have shown that oxides and hydroxides of these metals are better soluble in sulfuric acid than in hydrochloric, nitric, oxalic and phosphoric. This article presents experimental studies on the effect of sulfuric acid concentration on the rate of heterogeneous reaction of chromium (III) and aluminum (III) hydroxides. It is established that the rate of dissolution of hydroxides increases with increasing concentration of sulfuric acid. Moreover, the rate of transition of aluminum (III) ions from hydroxide is higher than the rate of transition of chromium (III) ions, under the same conditions. To calculate the main kinetic parameters, a model of a chain mechanism was selected. The dissolution simulation was carried out using the mathematical computer program MathCad. The need for real models is associated with the need to optimize ore leaching technologies, regulate the physico-chemical processes of oxide dissolution, scale etching and removal of deposits from thermal power equipment. Experimental studies have made it possible to determine that the rate of dissolution is limited by the formation and subsequent transition of surface compounds of the form: into an electrolyte solution. Such studies will help to create a generalized mechanism for the heterogeneous process of dissolution of aluminum and chromium oxides in acidic media.