Abstract Titanium dioxide (TiO 2) nano-fibers doped with Gd 3+ were synthesized by two-step synthesis method. The formed fibers were visualized from transmission electron microscopy (TEM) and X-ray diffraction (XRD). The results showed that the average diameter of the TiO 2 nano-fibers was 60–80 nm and the length of fibers was in the range of 6–7 μm. The TiO 2 nano-fibers doped with Gd 3+ heat treated in glycerol solvent had smaller crystal size than those without heat treatment. However, the size of TiO 2 nano-fibers decreased with increasing the heating temperature. The results obtained in the photocatalytic degradation of methyl orange indicated that the photocatalytic activity of the TiO 2 nano-fibers doped with Gd 3+ appeared a little reduction relative to that of TiO 2 nanopowders.