Herein discussed is a method of producing hydrogen comprising: providing a tubular reactor having an open end and a closed end, wherein the reactor comprises an anode on the inside and a cathode on the outside separated by and in contact with a mixed conducting electrolyte, wherein the electrolyte comprises an electronically conducting phase and an ionically conducting phase, wherein the reactor comprises no current collector or interconnect; introducing a hydrocarbon and an oxidant into a feed tube, wherein the feed tube contains a catalyst that promotes catalytic partial oxidation (CPOX) reactions, wherein the feed tube extends into the open end of the reactor and toward the closed end of the reactor; introducing steam to the outside of the tubular reactor; and converting steam to hydrogen electrochemically without electricity input.