The catalytic activity, selectivity to xylenes and time-on-stream stability were investigated in the transalkylation of toluene with 1, 2, 4-trimethylbenzene. The catalytic tests were carried out in a fixed bed reactor over zeolite Beta (Si/Al = 12.5, 75 and 150) and Y (Si/Al = 2.6, 6, 15 and 30). The operating parameters used were 400 °C, 1.0 Mpa, H2/HC = 4 and WHSV of 5 h-1. The length of each catalytic testing experiment was 50 hours, and for zeolite beta samples, the highest stability and selectivity to xylenes were achieved using the lowest Si/Al ratio with conversion of 41 wt. % and selectivity of 61 wt. %. In contrast, zeolites Y with Si/Al ratio of 2.6 showed the highest deactivation rate, whereas Y zeolites with Si/Al = 6 – 30 exhibited similar conversion (~ 27 wt. %) and selectivity to xylenes (~ 43 wt. %). The effects of Brønsted and Lewis acid sites on catalytic results are discussed.