Hydroxyapatite is a well-known biocompatible material which is widely used as bone graft and bone cement. In this study, hydroxyapatite was extracted from red snapper bone waste using mechanochemical methods. This study aims to optimize the milling time of the hydroxyapatite extraction process from red snapper bone waste. The extraction process begins by grinding the bone into a fine powder and then soaking it in chloroform while sonicating and drying. Then NaOH was added to the powder in a cylindrical jar and after that the mixture was ground with various grinding times. The milling products were then characterized by thermal gravimetric analysis (TGA), Fourier transform infra-red (FTIR) and X-ray diffraction (XRD). The results showed that there was a decrease in mass loss at each additional milling time with the largest loss at 30 minutes of milling and the smallest loss at 480 minutes of milling. TGA analysis also revealed a decrease in mass with each increase in milling time when the sample was heated from 30°C to 25°C. FTIR analysis showed that the red snapper bone powder contained CH and CN organic groups from samples with milling times of 30 and 60 minutes, while the typical hydroxyapatite functional groups, namely OH−, PO43-, and CO32-, were present in all samples. The presence of the CO32- group was also confirmed by XRD where type B hydroxyapatite appeared as the secondary phase. XRD analysis also informed that the crystal size of all samples of Red Snapper fish bones was in the range of 8.61 – 21.51 nm with a degree of crystallinity of 28.53 to 48.43% and the Ca/P molar ratio was from 1.69 – 1.93. Therefore, based on material decomposition, crystal structure, crystal size and Ca/P molar ratio, it can be concluded that the optimum milling time in this process is about 120 minutes. [ABSTRACT FROM AUTHOR]