We have developed an electrochemical process to convert waste polyolefins such as polyethylene (PE) and polypropylene (PP) into mono- and di-carboxylic acids via the electro-Fenton reaction at room temperature and atmospheric pressure. The polymers are fist functionalized with sulfonic groups and then grafted with co-catalysts (FeCl3). The treated polymer is then placed in an electrochemical cell contained carbon electrodes (cathode) that in-situ generated H2O2 via the oxygen reduction reaction (ORR: O2 + 2e- + 2H+ → H2O2) and H2 via the hydrogen evolution reaction (HER: 2e- + 2H+ → H2)as well as regenerated the co-catalysts ( Fe3+ + e- → Fe2+). We used a Pt-mess anode to perform the oxygen evolution reaction (OER: 2H2O → O2 + 4e- + 4H+); however, other non-precious anodes can be used as well. Hydroxyl radicals (·OH) were generated in situ via the Fenton reaction (Fe2+ + H2O2 → Fe2+ + OH- + ·OH) and depolymerized PE selectively into oxalic acid. The excess H+ and e- are recombined into H2.