A Cu-based 1D coordination polymer (Cu-1D-CP), [Cu-3(bpy)(3)(mu-OH)(2)(mu-CO3)(2)](n) has been synthesized and examined for its oxygen reduction reaction (ORR) activity in O-2 saturated 0.1 M KOH medium. Single crystal XRD study indicated the presence of two different Cu centers, mononuclear and binuclear, in Cu-1D-CP. Cu-1D-CP was supported on Ketjenblack carbon (Cu-1D-CP/C) to impart required electronically conducting path up to the Cu-active centers. Immobilization of mononuclear and binuclear sites was achieved by coating Cu-1D-CP/C layer with Nafion ionomer. Based on cyclic voltammetry and density functional theory, it was inferred that carbon and mononuclear-Cu center to facilitate 2-electron reduction of O-2 into HO2- and binuclear-Cu centers to facilitate 4-electron reduction of O-2. Complete reduction of O-2 by the latter is due to efficient overlap of HOMO of the binuclear site with the LUMO of O-2 molecule in side-on and bridging modes of O-2 adsorption. Even after 500 cycles of CV in O-2 saturated 0.1 M KOH electrolyte, the ORR activity of the Cu-1D-CP nearly unaffected indicating presence of stable Cu-active sites under the coulostatic stabilization of Nafion. (C) The Author(s) 2019. Published by ECS.