It has been proposed that the conductivity of a porous semiconductor, such as oxide‐coated cathode, may be influenced by the presence of an electron gas in the pores of the aggregate. In this paper calculations for the magnitude of this component of the conductivity are made on the basis of two simplified models approximating the geometry of a pore. The conditions under which such a component of the conductivity can appreciably modify the total conductivity are analyzed. It is further shown that such a porous semiconductor will possess two sources of thermoelectric emf. A simple theory for the thermoelectric power of the electron gas in a pore is developed, and the manner in which it will combine with the normal thermoelectric power of the crystals is shown.