Herein discussed is a method of producing hydrogen comprising introducing a metal smelter effluent gas or a basic oxygen furnace (BOF) effluent gas or a mixture thereof into an electrochemical (EC) reactor, wherein the EC reactor comprises a mixed-conducting membrane. In an embodiment, the method comprises introducing steam into the EC reactor on one side of the membrane, wherein the effluent gas is on the opposite side of the membrane, wherein the effluent gas and the steam are separated by the membrane and do not come in contact with each other.