New porous zeolite based membranes were synthesized using a ceramic methodology and characterized by means of XRD, SEM, EDAX and permeation tests. The membranes were produced by thermal transformation of natural clinoptilolite. The XRD study showed clinoptilolite amorphization at 600-900 degrees C. A posterior recrystallization to a siliceous phase and a compact aluminosilicate phase at 900-1150 degrees C was also produced. The Permeability [B] and Permeance [Pi] of H-2 and CO2 were measured using the Darcy Law correlation. It was also applied for gaseous laminar flow using the Carman-Kozeny equation. With the help of this equation the membrane pores sizes were measured. It was shown that the membrane porosity can be controlled by the grain size of the original natural zeolite powder. The membranes were further transformed by hydrothermal synthesis to obtain materials covered with an AlPO4-5 molecular sieve. In conclusion, novel, inexpensive, strong, high permeation rate, and high temperature membranes were produced with natural clinoptilolite, a low cost and available material.