Hydroxyapatite is the main mineral component in bones and teeth, thus being an important material in bone tissue engi-neering, e.g., for replacement and elimination of defects. Hydroxyapatite is widely used in real-life applications due to excellent biocom-patibility and bioactivity. Wet precipitation synthesis of hydroxyapatite is limited by diffusivity. Hence, choice of a diffusion modelbecomes critical. The purpose of this work is three-fold. It experimentally validates the use of Ginstling–Brounshtein model for hydroxy-apatite synthesis. It determines the effect of Ca(OH)2 concentration on the kinetics and reports a modified model to account for this phe-nomenon. It reports obtained kinetic constants that describe hydroxyapatite synthesis. Methods: Particle size was determined using scanningelectron microscopy and digital microscopy. Conversion kinetics were monitored using powder X-ray diffraction. Results: Experimentalvalidation was provided. Furthermore, the process was found dependent on the calcium hydroxide concentration and the model wasmodified to account for this phenomenon. Kinetic constants describing the synthesis of hydroxyapatite were obtained and reported.Conclusions: The model was well consistent with the experimental data and can be used for describing synthesis of hydroxyapatite forvarious suspension concentrations.