In this research, the synthesis of nanocrystalline merwinite (2SiO 2 –3CaO–MgO) bioactive ceramic was carried out by the sol–gel method. After crushing, obtained sol–gel derived bioceramic powder pressed uniaxially to produce cylindrical-like pellets, followed by sintering at 1300°C. Via immersion in simulated body fluid (SBF) for various time intervals, the formation of apatite was characterized. Scanning electron microscopy (SEM), X-ray diffraction analysis (XRD), and Fourier transform infrared spectroscopy (FT-IR) studies were conducted both before and after immersion in SBF. The crystallization temperature of the merwinite was determined by thermal analysis. Attained results confirmed formation of apatite layer within the first day of soaking. Accordingly it can be concluded that merwinite is bioactive and might be used for preparation of implantable biomaterials.