The development of gas separation membranes able to work at high temperatures require robust and thin ceramic layers. In this work, zirconia membranes have been prepared by the sol-gel method, following the colloidal sol route. The microporosity and crystallinity of the ZrO2 material was tested by N2 adsorption and XRD. The derived active zirconia layers were defect-free as seen by SEM. The optimum firing temperature range was set in the range 400-500 degrees C. He, H2, CO2, N2 gas permeation was conducted at temperatures up to 200 degrees C. High permeances were obtained and the microporosity of the zirconia layer was confirmed.