This study was conducted as an attempt to reach the best method to synthesis zinc oxide nanoparticles (ZnONPs) using chemical methods. ZnO nanoparticles was prepared using Sol-Gel method from zinc chloride (ZnCl2) and sodium hydroxide (NaOH) as chemical reactors and polyethylene glycol with low molecular weight as surfactant. The effect of the different reaction's temperature on the produced ZnO nanoparticles was studied. Four samples of zinc oxide nanoparticleswere prepared on different reaction's temperatures; 0 °C, 50 °C, 90 °C, and 0-RT °C (the reaction beginning at 0 °C and after that increase the temperature to reach the RT). The obtained products were examined usingdifferent techniques; X-ray Diffraction (XRD), High Resolution Scanning Electron Microscope (HRSEM), Fourier Transform Infrared (FT-IR), Ultraviolet–Visible Spectroscopy (UV-Vis), and Energy Dispersive X-ray Analysis (EDAX). The results showed that XRD, FT-IR, and EDAX confirmed the presence of ZnO nanoparticles with high purity. The UV-Vis. absorption spectrum showed an absorption band at 376 nm due to ZnO nanoparticles. HRSEM showed the superiority of ZnO nanoparticles that synthesized at 50 °C and the inferiority of that synthesized at 0-RT °C.