ZnO-NiO mixed oxide nanofibers have been successfully produced from a solution containing poly 4-vinyl phenol and Zn and Ni acetic acids by an electrospinning method. The calcination process of the ZnO-NiO/PVP composite nanofibers brings forth polycrystalline two-phase ZnO-NiO nanofibers of 3050 nm in diameters. ZnO and NiO crystallize into wurtzite and rock salt structures, respectively. The electrical conductivity of ZnO-NiO nanofibers increases with an increase in temperature, which has been attributed to the thermal emission of carrier from the energy state of the grain boundaries. The activation was estimated to be 0.5 eV. The capacitance of Zno-NiO nanofibers upon NO, gas exposure was observed to decrease. The feasibility of producing Zno-NiO mixed oxide nanofibers opens a new door for capacitive gas sensors. (C) 2009 Elsevier B.V. All rights reserved.