Transformations of 2-methylthiophene and benzothiophene together with n-undecane, declaim, or cumene under conditions of catalytic cracking have been studied. It has been found that enhancement of the [H]-donating activity in the order cumene < n-undecane < decalin leads to an increase in the degree of conversion of organic sulfur compounds, predominantly yielding hydrogen sulfide. An increase in the amount of 2-methylthiophene and benzothiophene alkylation and condensation products in the liquid products of cracking is observed in this case. Schemes of conversion of these compounds under catalytic cracking conditions have been proposed. The dependence of the degree of conversion of thiophene compounds into hydrogen sulfide on the ability of the catalyst to mediate hydrogen transfer reactions has been revealed.