Ex-cell synthesis of o-chlorobenzaldehyde from o-chlorotoluene was carried out using Mn3+ in sulfuric acid as a mediator. Reaction conditions were optimized to obtain maximum oxidation efficiency for the aldehyde. Reuse of the spent mediator requires its regeneration; however, this results in low current efficiency. Thus, electrolyte containing the mediator was treated by different techniques to maintain the current efficiency of catalyst regeneration, during recycle, at the initial value.