Abstract The aim was to investigate the feasibility of using a device to characterize permeability in porous substrates with low gas flux. Al2O3 supports were prepared by dry pressing using 1 to 3 wt% of polyethylene glycol (PEG) as a pore-forming agent. The green body was partially sintered at 1300 ºC. CO2 gas was used to measure both the pressure loss and the gas flux passing through the porous substrate. The permeability behavior was analyzed by the Darcy and Forchheimer models. The correlation between Darcy’s and Forchheimer’s permeabilities showed that the porous substrates may be used as membranes for micro, ultra, and nanofiltration. The mechanical resistance and the gas permeability exhibited antagonistic dependencies in relation to porosity, being identified as an optimized condition at 2 wt% PEG, in which the two properties presented high values.