Abstract: A process and apparatus are described for producing higher hydrocarbons from lower hydrocarbons, e.g. by gas phase electrocatalytic polymerization of methane. This is done using an electrolysis cell having an anode chamber on one side of a solid electrolyte and a cathode chamber on the other side of the solid electrolyte. According to this process, methane-containing gas is passed through the anode chamber to contact a catalytic anode which is connected to one side of the solid electrolyte, this solid electrolyte comprising a solid proton conducting membrane. An inert gas or oxygen is passed through the cathode chamber to contact a catalytic cathode which is connected to the other side of the proton conducting membrane. The membrane is designed so that H+ is capable of passing through the membrane from the anode chamber to the cathode chamber.