Hydrogen peroxide (H O ) is an effective green oxidant, which has been widely applied for environmental remediation. Here, we prepared a novel aluminum-graphite (Al-Gr) composite, which was capable of high-efficient production of H O through selective O reduction via a two-electron pathway. We discovered the production of H O at a wide pH range, which could be enhanced by optimizing Al-Gr synthesis conditions. Poly(ethylene glycol) (PEG) addition could promote the formation of a welding interface and porous structure between Al and Gr in the Al-Gr composite, which enhanced the galvanic corrosion of Al , the selectivity of oxygen reduction via the two-electron pathway, and the mass transfer of O in the Al-Gr/O system. The formation of Al C could be regulated by sintering temperature and sintering time, which could promote the intergranular corrosion of Al and enhance the mass transfer of O by reaction with water to generate the porous structure in the Al-Gr composite. The concentration of H O reached 777.5 mg/L at an initial pH of 9.0, an Al-Gr dosage of 8 g/L, and an O gas flow rate of 400 mL/min. The possible mechanisms of Al-Gr synthesis and H O production in the Al-Gr/O system were proposed. The Al-Gr composite was effective for the in situ production of H O , which could be further decomposed into a hydroxyl radical ( OH) by Al in the Al-Gr composite. This composite could be used not only to decolorize the Rhodamine B dye but also to degrade various organic contaminants in different water matrices, indicating its environmental significance.