Lanthanide ions (La(3+), Nd(3+), Sm(3+), Eu(3+), Gd(3+), and Yb(3+))/doped TiO2 nanoparticles were successfully synthesized by sol-gel method. Their photocatalytic activities were evaluated using Direct Blue dye (DB53) as a decomposition objective. The structural features of TiO2 and lanthanide ions/TiO2 were investigated by XRD, SEM, UV-diffuse reflectance, and nitrogen adsorption measurements. Our findings indicated that XRD data characteristic anatase phase reflections and also XRD analysis showed that lanthanides phase was not observed on Lanthanide ions/TiO2. The results indicated that Gd(3+)/TiO2 has the lowest bandgap and particle size and also the highest surface area and pore volume (V(p)) as well. Lanthanide ions can enhance the photocatalytic activity of TiO2 to some extent as compared with pure TiO2 and it was found that Gd(3+)/TiO2 is the most effective photocatalyst. The photocatalytic tests indicate that at the optimum conditions; illumination time 40 min, pH approximately 4, 0.3g/L photocatalyst loading and 100 ppm DB53; the dye removal efficiency was 100%. Details of the synthesis procedure and results of the characterization studies of the produced lanthanide ions/TiO2 are presented in this paper.