Nickel Oxide (NiO) thin films have a wide range of applications in the field of photovoltaics and optoelectronics technology, due to their excellent properties. By modifying the composition and state of the structure with heat treatments, most of the properties of the film are improved. Thus, this study aim to show the behavior of NiO thin films with the post-heat treatment. We prepared thin films of nickel oxide (NiO) by the spray pyrolysis method, deposited on glass substrates and heated to different temperatures (200 °C, 250 °C and 300 °C). The obtained samples were characterized by UV-Visible spectroscopy, contact angle measurement and Raman spectroscopy. We found that the transmittance of films increases with the annealing temperature and Urbach energy (disorder) decreases with increasing optics gap and annealing temperature. Also, the contact angle increases with the temperature of the annealing, but the surface remains hydrophilic. Furthermore, the Raman spectrum has shown the presence of the crystalline state and amorphous carbon (graphite).