<p>Density Functional Theory (DFT) is used to investigate the optical, electrical and vibrational properties of titanium dioxide nanoparticles (TiO₂NPs) by altering the solvent conditions from water to ethanol. From the theoretical calculations, it was observed that their HOMO (highest occupied molecular orbital) and LUMO (lowest unoccupied molecular orbital) energy gaps are comparable with the experimental results. To study the electronic properties in detail, Koopmans’ formulas are utilised to determine the binding energy per atom, energy gap, chemical potential, ionization potential, electron affinity, hardness and electrophilicity index. These parameters were calculated at the level of B3LYP with the LANL2DZ basis set using GAUSSIAN-09 software. The IR (Infra-red) and Raman spectra of the proposed nanoparticles under different solvent conditions reveal the absorption and vibrational modes present in the system. In addition, simulated IR and Raman spectra revealed distinct shifts in the vibrational modes, especially in ethanol-mediated TiO₂ NPs, a shift toward higher wavenumbers was observed, suggesting enhanced bond stiffness and improved crystallinity. Overall, the study provides a comprehensive theoretical insight into the role of solvent environment in tailoring the physicochemical properties of TiO₂ NPs, which is important for their applications in sensing, photocatalysis, optoelectronic devices, and energy-related technologies.This provides a clear indication of the solvent’s effect on the physical and chemical properties of the TiO₂NPs.</p>