Kaolin with a given size distribution was calcined at 1023 K for 2 h then digested in 3 0, 4 5, and 60 N sulfuric acid at constant temperatures within the range 328-358 K The samples taken from the solution at predetermined time intervals were analyzed by using a complexometric method and the amount of aluminum passed into the solution was determined The results showed that the dissolution kinetics follow the shrinking core model for spherical particles of unchanging size, t/tau = 1 - (1 - x(B))(1/3), with the apparent activation energy of 98 4 kJ/mol The leaching reaction was found to be the 0 75th order with respect to acid concentration and controlled by reaction step