The permporometry technique, common in the fields of thin filters, membranes etc., was extended to porous solids with far larger thicknesses. The basic idea of permporometry is the controlled expulsion of a suitable liquid from pores of different sizes by increasing the gas pressure difference across the tested porous solid. The gas flow rate through liquid-free pores then corresponds to the amount of pores with different sizes. Two modes of measurement were suggested and tested. The contribution of the Knudsen flow mechanism was taken into account in addition to the usually anticipated viscous gas flow mechanism. It was confirmed that both measurement modes give consistent pore size distributions (PSD) of flow-through pores. Permporometry PSDs were compared with results from mercury porosimetry and pseudo-steady state permeation. It appears that permporometry should be considered as a standard textural characterization technique suitable for the prediction and simulation of gas flow through porous media in all processes where gas transport takes place.