Dehydroalkylation of methylcyclohexane with methanol on modified forms of mordenite and pentasil was studied. It was shown that xylene isomers are formed in the temperature range of 500-530degreesC via two parallel pathways, dehydroalkylation and dehydrodisproportionation of methylcyclohexane. As the temperature was elevated from 530 to 570degreesC, the methylcyclohexane conversion via dehydroalkylation changed insignificantly but the degree of conversion through dehydrodisproportionation sharply increased. The highest activity was shown by HNa-mordenite modified with phosphorous and gallium and gadolinium oxides.