Zn-doped TiO2 nanoparticles (Z-T NPs) were successfully synthesized using the sol-gel method. Titanium isopropoxide, ethanol, and diethanolamine were used in the ratio of 1:6:1 as the metal precursor, solvent precursor, and refluxing agent, respectively. The Z-T NPs were characterized using Fourier Transform Infrared (FTIR), X-ray Diffraction (XRD), Scanning Electron Microscope (SEM), and UV-Vis reflectance spectroscopy. FTIR analysis showed vibrations in the fingerprint region at wave number 668 cm-1, which were attributed to the Zn-O stretching vibration, and at wave number 1033 cm-1 for Ti-O-Zn asymmetrical stretching vibration. XRD analysis of the 0% Z-T NPs showed the formation of the anatase phase with the plane (200) as the preferred orientation. An increase of Zn % mol caused planes (105) and (211) to convolve. Debye-Scherer equation showed crystallite size decreased when the Zn dopants were introduced; 10% had the smallest crystallite size and 5% had the largest crystallite size. The crystallite size was inversely proportional to Specific Surface Area, Dislocation density, and Full Width at Half Maximum. SEM images indicated improved crystal structure with increased sintering, aggregation, and agglomeration. EDS endorsed the doping process by having Zn atoms in the doped Z-T NPs. The optical analysis showed an increase in band gap energy from 4.43 to 5.14 eV for 0% and 3% Z–T NPs, respectively.