A transport equation for multicomponent dithrsion through porous media, which has been proposed in the literature, is tested experimentahy by studying the pressure dependence of ternary diffusion (pH,/oH,/He resp. pH,loH,/Arl through a fritted glass disk with a mean pore radius of P = 1~. The diffusion resistance has been measured in a pressure range between 2 and nearly 600 mm Hg using the experimental method of the "diffusion-reaction cell". The linear dependence on pressure predicted theoretically has been observed for higher pressures only (p > 200 mm Hg). At lower pressures considerable deviations from the expected linear behavior can be found. In particular, at low pressures a minimum is observed in the resistance vs. pressure relationship. Taking into account the additional resistances due to the finite length of the transport pores one can partiaIIy explain these deviations. Finally the results are used to calculate the pressure dependence of the effectiveness factor for diffusion controlled o-p-H, conversion. At low pressures lower values for this factor are obtained than predicted by the equation mentioned above. A surprising result is that the pressure dependence of the effectiveness factor shows a minimum for the o-p-I-&-He mixtures.