Mesoporous TiO2 nanofibers with controlled diameter, crystal size, and anatase versus rutile crystal structures are produced by calcination at 500-700 degrees C of precursor nanofibers of polyvinylpyrrolidone and titanium isopropoxide, obtained from a scalable gas jet fiber spinning process. These TiO2 nanofibers are used in the photocatalytic oxidation of gas-phase ethanol at room temperature on exposure to UV irradiation. The experimental trends are analyzed using electron-hole (e-h) charge recombination inferred from high-intensity photoluminescence emission spectra, specific surface area, crystallinity, and the proportions of anatase and rutile phases. The nanofibers show a photocatalytic activity that is up to an order of magnitude higher than that of commercial-grade P25 TiO2 nanoparticles because of slower e-h recombination phenomena in the former. The results show that ethanol undergoes complete oxidation into CO2 and H2O on the nanofibers without the accumulation of the intermediate products acetaldehyde and formic acid.