We report a semiconducting metal-organic graphene analog, Ni3(HITP)2, with an adjustable crystalline structure for mediating efficient selectivity toward hydrogen peroxide. The as-prepared 5-Ni3(HITP)2 catalyst with low crystallinity can electrocatalyze O2 to H2O2 with a high selectivity of 80% over a wide potential range of 0.2-0.6 V vs. RHE and with a large mass activity of 292 A gNi-1 at 0.25 V in 0.1 M KOH.