The feasibility of using reactive ion-exchange for the determination of oxalate in aqueous solution has been demonstrated. The procedure consists of pH adjustment of the analyte solution, concentration of oxalate on a lead(II)-loaded cation exchange mini-column in the form of lead oxalate precipitate, reactive elution of oxalate by sulphuric acid dissolution and analysis of the concentrated eluate by permanganate titration. Almost quantitative yields of oxalate are obtained for concentrations typically found in human urine. The procedure represents a simple and reliable technique to concentrate oxalate for determination by classical methods.