Lanthanide ions  (La³⁺, Nd³⁺, Sm³⁺, Eu³⁺, Gd³⁺, and Yb³⁺)- doped TiO₂ nanoparticles were successfully synthesized by sol-gel method to enhance the photocatalytic activity of the developed materials. The structural features of TiO2 and lanthanide ions–doped TiO2 fired at 550ºC were investigated by XRD, UV-diffuse reflectance, and nitrogen adsorption measurements. The effect of lanthanide ions-doped TiO₂ on the photoactivity was evaluated by the degradation of direct blue dye (DB 53) as a probe reaction. Our findings indicated that XRD data verified the formation of typical characteristic anatase reflections without any separate dopant-related peaks in all the prepared lanthanide ion-doped TiO₂ nanoparticles. The particle size of lanthanide ions-doped TiO₂ nanoparticles was smaller than pure TiO₂ indicating the improvement of its surface morphology. The results indicated that Gd³⁺-TiO₂ has the lowest bandgap and particle size and the highest surface area and pore volume (Vp) as well. The photocatalytic behavior of lanthanide ions-doped TiO₂ was tested for oxidation of DB 53 in the presence of UV light at λ = 365 nm. It was found that Gd³⁺-TiO₂ is the most effective catalyst in the photocatalytic activity studies. That might be due to its special characteristics of particle size, surface texture and bandgap properties. Our results should provide a significant contribution to the understanding of the chemistry of lanthanide iondoped TiO₂ systems. Details of the synthesis procedure and results of the characterization studies of the produced lanthanide ions-TiO₂ are presented in this paper.