<p>Hydroxyapatite (HAp; Ca₁₀(PO₄)₆(OH)₂) is a primary inorganic component found in bone, enamel, and dentine, and it is also present in certain plant sources. As one of the most extensively studied biominerals, HAp plays a crucial role in biomedical applications, including tissue engineering, drug delivery, biomedical research, and bone regeneration. While natural sources of HAp exist, synthetic approaches offer greater control over particle size, morphology, and crystallinity, which are central concerns in current research due to their impact on material properties and applications. In this study, we synthesized hydroxyapatite nanoparticles (nHAp) using a wet-chemical precipitation method performed at room temperature in an aqueous solution. We systematically investigated the influence of three different additives - salicylic acid, gallic acid, and para-hydroxybenzoic acid - on the morphology of nHAp. Each additive resulted in distinct nanoparticle morphologies, with higher concentrations leading to a gradual transition from rod-shaped to sheet-like structures. Comprehensive characterization of the synthesized nHAp was performed using Fourier-transform infrared spectroscopy (FTIR), powder X-ray diffraction (PXRD), and field emission scanning electron microscopy (FESM) to analyze structural, chemical, and morphological properties. This work highlights the significance of additive selection and concentration in tailoring the properties of nHAp for advanced biomedical applications.</p>