Abstract <p>Metal-doped titanium dioxide nanoparticles are being used in many applications such as water treatment due to its high photocatalytic activity. Yttrium-doped titanium dioxide (TiO₂) nanoparticles were synthesized by hydrothermal method at a temperature of 120°C. Various solvent treatment and thermal annealing methods were investigated to obtain nanoparticles of a specific size and minimal residual carbon content. The width of the band gap of nanoparticles was estimated using diffuse reflectance spectroscopy data. Photoluminescence properties of the materials were evaluated at an excitation wavelength of 473 nm. Doped TiO₂ nanoparticles exhibit enhanced photocatalytic activity in the reaction of decomposition of methylene blue (MB), which is believed to be due to the presence of additional energy levels within the forbidden zone, as well as improved separation of electron-hole pairs with a decrease in recombination. These results contribute to a deeper understanding of the potential applications of Y-doped TiO₂ nanoparticles in photocatalysis and underscore the importance of understanding the synthesis and characterization of such materials for future research and developments in improving water quality to make it appropriate for a specific end-use.</p>