Hydroxyapatite (HAp) with the chemical formula of Ca10(PO4)6(OH)2 is a mineral component found in bone structure, and has broad application in many fields. Several sources can be used for the extraction of HAp either synthetic or natural. However, sources such as porcine and bovine have drawbacks that decreased the demand of HAp.This study aimed toextract and determine particle size distribution and pore characteristics ofhydroxyapatite nanoparticles (HAp NPs) derived from spotted sardinella (Amblygaster sirm). Further characterization of extracted HAp NPswas carried out by Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDS)and Brunauer–Emmett–Teller(BET).SEM analysis has shown that the extracted HApNPs has an irregular sphere-like shape with particle size distribution ranged from 95nm to 100nm. The EDS analysis confirmed the presence of calcium (Ca), phosphorus (P) in the extracted nano-HAp and the Ca/ P ratio was 1.64, which is acceptable for HApnon-stoichiometric molar ratio. Nitrogen sorption analysis demonstrated that the extracted HAp NPs has high specific surface area and pore volume which was 22.07 m2/g and 0.1179 cm3/g, respectively. HAp NPs demonstrated similar properties to the standard HAp and possessed excellent physico-chemical properties due to the nanoparticle size that contribute to the large specific surface area. Overall findings have demostrated that the extracted HAp NPs from spotted sardinella bone had successfully produce nonstoichiometric HAp NPs with a large specific surface area. Such characteristics is important for HAp NPs that differed itself from conventional-sized HAp. This study suggested that the synthesized HAp NPs could be potentially used as an alternative materials for various applications.