NOVELTY - Oxalic acid and co-products are produced by receiving anolyte feed including hydrogen halide at anolyte region of 1st electrochemical cell with an anode, receiving catholyte feed with carbon dioxide and alkali metal bicarbonate at catholyte region of 1st electrochemical cell including cathode, applying electrical potential between anode and cathode to form formate and halogen, converting formate to alkali metal oxalate, converting alkali metal oxalate to oxalic acid and co-producing alkali metal hydroxide, hydrogen, and halogen, and converting alkali metal halide to produce hydrogen halide.    USE - Production of oxalic acid and co-products.    ADVANTAGE - The anolyte brine concentration may be operated at lower sodium chloride concentrations, which may result in a decrease in chlorine efficiency and generation of more byproduct oxygen in the chlorine gas stream, but which may be useful in reducing brine flow rate through the brine purification system with a reduction in brine processing costs.    DETAILED DESCRIPTION - Oxalic acid and co-products are produced by receiving anolyte feed including hydrogen halide at anolyte region of 1st electrochemical cell including an anode, receiving catholyte feed including carbon dioxide and alkali metal bicarbonate at catholyte region of 1st electrochemical cell including cathode, applying electrical potential between anode and cathode of 1st electrochemical cell sufficient to reduce carbon dioxide to formate and oxidize hydrogen halide to halogen, converting formate to alkali metal oxalate via thermal reaction, receiving alkali metal oxalate at 1st electrochemical acidification electrolyzer, converting alkali metal oxalate to oxalic acid and co-producing alkali metal hydroxide, hydrogen, and halogen at 1st electrochemical acidification electrolyzer, converting alkali metal halide in 2nd electrochemical acidification electrolyzer to produce hydrogen halide containing solution, alkali metal hydroxide, and hydrogen, feeding at least a portion of hydrogen halide containing solution to anolyte region of 1st electrochemical cell, and feeding at least a portion of hydrogen halide containing solution to 1st electrochemical acidification electrolyzer. An INDEPENDENT CLAIM is included for production of formic acid and co-products which involves receiving anolyte feed including hydrogen halide at anolyte region of 1st electrochemical cell including an anode, receiving catholyte feed including carbon dioxide and alkali metal bicarbonate at catholyte region of 1st electrochemical cell including a cathode, applying electrical potential between anode and cathode sufficient to reduce carbon dioxide to at least alkali metal formate and oxidize hydrogen halide to halogen, converting alkali metal formate to formic acid and co-producing alkali metal hydroxide, hydrogen, and halogen at 1st electrochemical acidification electrolyzer, converting alkali metal halide in 2nd electrochemical acidification electrolyzer to produce hydrogen halide containing solution, alkali metal hydroxide, and hydrogen, feeding at least a portion of hydrogen halide containing solution to anolyte compartment of 1st electrochemical cell, and feeding at least a portion of hydrogen halide containing solution to 1st electrochemical acidification electrolyzer.