​Zeolite NaA membranes were obtained by using a continuous recirculating flow, 0.25–5 ml min⁻¹ of synthesis solution along the inner side of asymmetric porous alumina tubular supports. The membranes of 5 μm in thickness showed a N₂ permeance of 5 × 10⁻⁷–1 × 10⁻⁶ m⁻² s⁻¹ Pa⁻¹. The procedure developed in this work provides control of the synthesis and crystallization conditions at any position on the tubular support, thus implying scale-up.