Abstract: A flow-through porous electrode structure for electrochemical systems having flowing electrolytes is disclosed. The flow-through porous electrode structure includes a single porous electrode having two planar opposing faces, each of which provides a reaction surface for electrochemical electron-transfer reactions of the same polarity. The porous electrode features spaced passage means which extends at least in part through the electrode between the opposing faces for distributing the circulating electrolyte through the electrode. The passage means comprises a plurality of vertically spaced, generally horizontally disposed passageways extending from a first side of the porous member. These passageways having a generally circular cross section and extend substantially across the width of the porous electrode member.