Mixed-phase TiO2 nanofibers prepared via a sol-gel technique followed by electrospinning and calcination are provided as photocatalysts. The calcination temperature is adjusted to control the rutile phase fraction in TiO2 nanofibers relative to the anatase phase. Post-calcined TiO2 nanofibers composed of 38 wt % rutile and 62 wt % anatase exhibited the highest initial rate constant of UV photocatalysis. This can be attributed to the combined influences of the fibers' specific surface areas and their phase compositions.