Influence of synthesis parameters; silica sources, relative alkalinity and silicon module, were investigated on preparation of T type zeolite by hydrothermal method, using a two level factorial design. Crystallization time and reaction temperature were held constant at 7 days and 378 K, respectively. The synthesized products were characterized by XRD and SEM techniques. The results showed that increasing silicon module and decreasing relative alkalinity in the synthesis gel improved the product relative crystallinity. It was also observed that using colloidal silica as the silica source improved crystallinity and phase purity of T type zeolites. The prepared zeolite T with the highest relative crystallinity was examined in the batch adsorption experiments at three temperatures of 288, 298 and 308 K and various pressures from 0.1 up to 2 MPa to verify the ability of the material for selective adsorption and separation of CO2 from CH4. The adsorption capacities and isotherms of CO2 and CH4 were determined at the studied temperatures. The results showed that the highest ideal selectivity of CO2/CH4 could be achieved at atmospheric pressure and 308 K. The performance of the adsorbent was confirmed with breakthrough curves and breakthrough times resulted from dynamic adsorption experiments of the mixed gases. (C) 2012 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.