Alkylation desulfurization of fluid catalytic cracking (FCC) gasoline over solid acid catalysts is considered to be a viable path to meet environmental regulations of sulfur emissions. However, side reactions in the process such as alkenes oligomerization and aromatic alkylation lead to the formation of significant amounts of coke, which will greatly reduce the catalyst lifetime and require keeping high catalyst selectivity for thiophenic compounds alkylation. In this paper, both the experimental and theoretical investigations were carried out to further explain the effect of methanol on the catalytic behavior of macroporous sulfonic resins Amberlyst 35 (A35) in the alkylation desulfurization process of FCC gasoline. The results indicated that adding suitable amount of methanol (about 1.0 wt% of the feed gasoline) was beneficial to improve the catalytic behavior of A35 in this process. The competition adsorption of suitable amount of methanol and its ether product with isoalkenes could greatly reduce the activated alkenes on the acid sites of A35 and have little impact on the alkylation of thiophenic sulfurs. They could also decrease the alkenes conversion for side reactions of alkenes oligomerization, which was favorable for improving the catalytic selectivity for thiophenic compounds alkylation and prolonging the catalytic lifetime of A35. (C) 2013 Elsevier Ltd. All rights reserved.