Abstract The present work reports the successful synthesis of nano-hydroxyapatite, Ca 10(PO 4) 6(OH) 2 (denoted HAP) from calcined eggshell by hydrothermal method using cationic surfactant (CTAB) as regulator of nucleation and crystal growth. The reaction involved in the synthesis was studied elaborately. The influence of reaction temperature, ageing time and CTAB concentration on the synthesis of nano-HAP are also studied in addition to the effect of sintering temperature on the crystal growth. Spectral characterization involving Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) techniques were performed for functional group analysis and phase identification of the materials, respectively. Thermal stability of nano-HAP was investigated by thermal analysis (TG/DTA). The physical characteristics, such as morphology and particle size of the synthesized nano-HAP were assessed thoroughly by scanning electron microscopy (SEM) and atomic force microscopy (AFM) techniques. The results have revealed that well-crystallized nano-HAP was synthesized by hydrothermal treatment at 160 °C for 10 h with the addition of CTAB at critical micelle concentration (CMC). It was also found that the synthesized nano-HAP was thermally stable up to 1100 °C.