Polyacrylonitrile (PAN) nanofiber webs containing titanium dioxide (TiO2) were prepared via electrospinning. Either dimethyl formamide (DMF) or its mixture with small amount of water (3 and 5%w/w.) was employed to prepare 5%w/w.PAN/DMF or PAN/DMF/H2O solution, respectively. Introducing non-solvent water in PAN/DMF/H2O solution was attempted to induce phase separation, which may lead to formation of porous structure on nanofibers surface. Different amounts of TiO2 (1 to 3 wt.%) were added into PAN/DMF/(H2O) solutions and then electrospun into nanofiber webs. From SEM, nanofibers possessed rough surfaces and had averaged diameters in ranges of 170–430 nm., showing tendency to increase with amount of TiO2 and water. Porous structure on fiber surfaces was not clearly observed, which was suspected to be due to insufficient amount of water employed. Less homogeneity in polymer solution due to presence of TiO2 disfavored increasing water content higher than 5%w/w. EDS data confirmed presence of TiO2 in electrospun webs. From photocatalysis evaluation, webs containing 2 and 3 wt.% TiO2 showed good photocatalytic activity such that 80 percent of 10 ppm. methylene blue degraded in 24 hours. Slight increase in photocatalytic activity was observed in webs obtained from PAN/DMF/H2O solutions.