The solvolyses, in 80% aqueous ethanol, of cis- and trans-3-hydroxy-2,2-4,4-tetramethylcyclobutyl tosylates and of cis- and trans-3-hydroxy-2,2,3,4,4-pentamethylcyclobutyl tosylates have been studied. The observed rate differences are explained in terms of steric effects on the transition states for the reactions. © 1969.