This study investigates the antibacterial efficacy of TiO₂ and TiO₂/Cu nanoparticles synthesized via the sol–gel method. The materials were characterized using various techniques, including SEM, TEM, EDS, XRD, FTIR, Raman spectroscopy, XPS, TGA, and BET analysis. The results showed that the nanoparticles had a spherical morphology, with Cu incorporation confirmed by EDS and XPS. XRD revealed the formation of tetragonal anatase phase TiO₂/Cu, while FTIR identified functional groups linked to the doped TiO₂. The thermal stability of TiO₂/Cu was lower than pure TiO₂. Both TiO₂ and TiO₂/Cu nanoparticles effectively inhibited the growth of Bacillus subtilis (B. subtilis) and Escherichia coli (E. coli), with antibacterial efficiencies of 90% and 80%, respectively, in the dark. The addition of Cu did not affect the antibacterial activity, possibly due to the lower weight content in the composites. The study highlights the potential of these nanoparticles as effective antibacterial agents for water treatment.This study investigates the antibacterial efficacy of TiO₂ and TiO₂/Cu nanoparticles synthesized via the sol–gel method. The materials were characterized using various techniques, including SEM, TEM, EDS, XRD, FTIR, Raman spectroscopy, XPS, TGA, and BET analysis. The results showed that the nanoparticles had a spherical morphology, with Cu incorporation confirmed by EDS and XPS. XRD revealed the formation of tetragonal anatase phase TiO₂/Cu, while FTIR identified functional groups linked to the doped TiO₂. The thermal stability of TiO₂/Cu was lower than pure TiO₂. Both TiO₂ and TiO₂/Cu nanoparticles effectively inhibited the growth of Bacillus subtilis (B. subtilis) and Escherichia coli (E. coli), with antibacterial efficiencies of 90% and 80%, respectively, in the dark. The addition of Cu did not affect the antibacterial activity, possibly due to the lower weight content in the composites. The study highlights the potential of these nanoparticles as effective antibacterial agents for water treatment.