AbstractSelective toluene disproportionation has been studied over ZSM‐5 zeolites modified withP, Si and Cs compounds. For thePand Si modified samples,p‐xylene proportion in the primary product was 100% due to the diffusional control on the internal xylene isomerization. The number and strength of the acid sites are reduced by the three modifier agents but a relationship between para‐selectivity and the decrease of the acid strength has not been observed. The most para‐selective samples have been those modified with Si which has been related to the deposition of this agent on the external surface of the zeolite crystals avoiding the primary product isomer