BACKGROUND: There is a demand to develop nano-photocatalyst that has better performance than existing TiO2 nanoparticles, which are difficult to separate and reuse. RESULTS: Both TiO2 and TiO2/ZnO composite nanofibers prepared using sol-gel assisted electrospinning provided higher photocatalytic oxidation (PCO) of NO than TiO2 nanoparticles of 100 nm. The nanopores formed between nano-crystallites of nanofibers were found to increase both adsorption and activity of the photocatalyst. The TiO2/ZnO composite nanofiber photocatalyst has a lower band-gap than TiO2 nanofibers, which favors photo-electron generation, because introduction of ZnO causes charge imbalance and formation of unsaturated chemical bonds on the surface, increasing the catalyst surface oxygen vacancy and generation of the oxidation radicals, thereby increasing PCO. The efficiency of PCO under irradiation containing a full spectrum of wavelengths was optimized by adding 0.10 wt% of Zn to the TiO2 photocatalyst, and this optimal amount of added dopant was in accord with X-ray photoelectron spectroscopy measurement. The activity of the nanofiber photocatalysts was improved by increasing the irradiation area and residence time; and optimized at a relative humidity of 50%. CONCLUSION: The present study demonstrates that enhanced PCO of NO with photocatalyst nanofiber can be optimized under solar light irradiation. (C) 2014 Society of Chemical Industry