A method for in situ reduction of the sulfur content in catalytic cracking gasoline is reported. A comparison of thermal and catalytic transformations of sulfide and thiophene sulfur is presented. Main transformations of various organosulfur compounds are demonstrated. The effect of [H]-donor activity of hydrocarbons on conversion of thiophene sulfur into hydrogen sulfide is revealed. The impact of acid-base properties of the additives to the cracking catalysts on sulfur content reduction in the liquid products is examined in detail (TPD-NH3, Al-27 NMR, CO2 adsorption). The choice of optimal qualitative composition of a modifying additive for reducing the sulfur content in catalytic cracking gasoline is substantiated. (C) 2012 Elsevier B.V. All rights reserved.