Abstract: A process is described for reducing the concentration of oxyhalogen impurities in an alkali metal halide brine recovered from an electrolytic cell which comprises circulating the alkali metal halide brine to a treatment zone outside of the electrolytic cell. Within the treatment zone, the alkali metal halide brine is reacted with oxalic acid while maintaining the alkali metal halide brine at a pH of less than about 4.5. A purified brine having a substantially reduced concentration of oxyhalogen impurities is recovered from the treatment zone. The process may be employed in treating brines recovered from mercury cells and membrane cells for the production of chlorine and alkali metal hydroxides and its employment results in a substantial reduction in the amount of concentrated acid required in brine treatment and a reduction in energy costs for brine purification.