Multi wall carbon nanotube (MWCNT) doped ZnO nanofibers were fabricated by electrospinning for the first time. We have successfully demonstrated the photocatalytic activity of doped nanofibers under visible light. Scanning electron microscopy showed that the diameter of MWCNT-doped ZnO nanofibers varied from 120 to 300 nm without agglomeration of MWCNT. Fourier transform infrared spectroscopy and X-ray diffraction studies proved the formation of Zn-O bond and wurtzite structure with smaller crystal size in doped nanofibers. Raman spectra demonstrated slight shift in bond position after nanofiber doping, indicating the chemical bond between MWCNT and ZnO. X-ray photoelectron spectroscopy showed that Zn-O-C bond were formed in the nanofibers and the energy band gaps were 3.11 and 2.94 eV for pure and doped ZnO nanofibers, respectively. Thermal gravimetric analysis revealed a total weight loss of 55% with no variation in mass reduction at temperature above 460 degrees C. In comparison with ZnO nanofibers, a 7-fold enhancement in photocatalytic activity was observed under UV light as a result of delaying electron-hole recombination as verified by photoluminescence spectroscopy. The improvement in the visible light photocatalytic performance was assigned to the role of MWCNT as photosensitizer and the synergistic effect between MWCNT and ZnO. (C) 2012 Elsevier B.V. All rights reserved.