Here, we report the synthesis of SAPO-34 employing the crystal growth inhibitors (PEG, C12E6 & MB) for both seed and secondary growth to decrease the crystal size and improve textural and morphological properties of SAPO-34 membranes. The use of crystal growth inhibitors produced membranes with ~0.6 µm crystal size and narrow particle size distribution displaying cubic and rectangular morphologies. The obtained SAPO-34 seeds were characterized by BET, XRD, SEM, FTIR, TGA and CO2/CH4 adsorption studies. The SAPO-34 crystals showed chabazite structure confirming the crystallinity of the material with surface areas up to ~700 m2/g. The SAPO-34 crystals were used as seeds and gels to prepare membranes on the inside surface of the tubular á-Al2O3 supports by hydrothermal treatment. The CO2/CH4 separation performance of synthesized SAPO-34 membranes was studied at different conditions of pressure and temperature.