NOVELTY - Producing a first product from a first region of an electrochemical cell (102) having a cathode and a second product from a second region of the electrochemical cell having an anode, involves contacting the first region with a catholyte, receiving a feed of a recycled reactant at the second region of the cell, contacting the second region with an anolyte, applying an electrical potential between the anode and the cathode, removing diatomic halide product from the second region, introducing the diatomic halide product to a secondary reactor, and forming the recycled reactant in the reactor.    USE - The method is useful for producing a first product from a first region of an electrochemical cell having a cathode and a second product from a second region of the electrochemical cell having an anode, where the first product includes carboxylic acid (preferred), carbon monoxide, formic acid, formaldehyde, methanol, methane, oxalate, oxalic acid, glyoxylic acid, glyoxylate, glycolic acid, glycolate, glyoxal, glycolaldehyde, ethylene glycol, acetic acid, acetate, acetaldehyde, ethanol, ethane, ethylene, lactic acid, lactate, propanoic acid, propionate, acetone, isopropanol, 1-propanol, 1,2-propylene glycol, propane, propylene, butane, butene, 1-butanol, 2-butanone, 2-butanol, a carboxylate, an aldehyde, an alcohol and a ketone, and the second product is bromine (all claimed), fluorine, chlorine and/or iodine.    DETAILED DESCRIPTION - Producing a first product from a first region of an electrochemical cell (102) having a cathode and a second product from a second region of the electrochemical cell having an anode, comprises contacting the first region with a catholyte comprising carbon dioxide, receiving a feed of a recycled reactant at the second region of the electrochemical cell, contacting the second region with an anolyte comprising the recycled reactant, applying an electrical potential between the anode and the cathode sufficient to produce a first product recoverable from the first region and a diatomic halide product (X2), recoverable from the second region, removing the diatomic halide product from the second region, introducing the diatomic halide product to a secondary reactor, and forming the recycled reactant in the secondary reactor. The recycled reactant is hydrogen halides (HX), where X is fluorine, chlorine, bromine or iodine. An INDEPENDENT CLAIM is included for a system for electrochemical co-production of products comprising an electrochemical cell (102) including a first region, a cathode associated with the first region, a second region, an anode associated with the second region and a separator for selectively controlling a flow of ions between the first region and the second region, a carbon dioxide source (104) in flow communication with the first region to supply carbon dioxide to the first region, a recycled reactant source in flow communication with the second region to supply a recycled reactant to the second region, an energy source for applying a current across the anode and the cathode, where the first product is recoverable from the first region and the second product is recoverable from the second region when current is applied, and a secondary reactor (106) including an alkane, alkene or aromatic, where the secondary reactor is configured to form the recycled reactant from the second product and the alkane, alkene or aromatic for introduction of the recycled reactant to the second region.    DESCRIPTION OF DRAWING(S) - The figure shows a block diagram of a system for electrochemical co-production of products.    Electrochemical cell (102)    Carbon dioxide source (104)    Secondary reactor (106)    Carbon-based reactant source (108)    First product extractor. (110)