Hydroxyapatite nanoparticles (HAp-NPs) were prepared using a precipitation route from an aqueous solution at a 1.66 Ca/P ion ratio and sintered at different temperatures. X-ray diffraction (XRD) was used to investigate the structural properties of the prepared films. Using a Field Emission Scanning Electron Microscope, the morphology of the surfaces was analyzed. Using Fourier Transform Infrared (FTIR) Spectroscopy, the surface's chemical composition and chemical bonding information were identified. The structural analysis shows that heating treatment reduced the broadening of diffraction peaks, enhancing the Hydroxyapatite phase crystallinity. No phase transition was observed as the sintering temperature increased, revealing the HAp phase's high stability. SEM micrograph images revealed a nanostructured foam-like structure that changed into a flake-shaped structure with diameters between 300 nm and 600 nm after heat treatment. FTIR spectroscopy results revealed that the heat treatment improved the crystallization of the developed HAp-NPs samples. Barrett-Joyner-Halenda (BJH) was used to determine the pore size of HAp NPs, whereas Brunauer-Emmett-Teller (BET) analysis was employed to characterize the surface area of the samples.