Using numerical calculations within a unidimensional model for porous electrodes (PE) and experimental methods (PE composed of layers of identical or different carbon felts, the anodic oxidation reaction in 0.01 M K4Fe(CN)6 + 0.01 M K3Fe(CN)6 + 1 M KOH), it is shown that, in contrast to a uniform porous matrix, where a decrease in the solid-phase conduction κs always leads to an increase in the ohmic voltage losses inside PE, for κs(x) varying across the PE thickness, the result depends on the κs profile. If κs decreases from the rear current lead to the PE front, and is higher or lower than the solution conduction in different regions of the solid phase, the entire increase in the effectively working area is reached with no increase in the losses. With a reverse κs profile, the matrix operation efficiency abruptly decreases and the losses increase.