Nanocrystalline forsterite (Mg2SiO4) powder was synthesized using sucrose as a chelating agent and template material from an aqueous solution of magnesium nitrate and colloidal silica. The synthesized powders were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), simultaneous thermal analysis (STA), and scanning electron microscopy (SEM). The synthesized nano-powder had particle size smaller than 200 nm and average crystallite size of powders calcined at 800 degrees C for 3 h was in the range of 10-30 nm. Also the effect of addition 2 and 4 wt.% forsterite seed on nucleation temperature and crystallite size of forsterite was investigated. The presence of small amounts Of Mg2SiO4 as seed obviously accelerated the crystallization of forsterite. According to DTA results the inceptive formation temperature Of Mg2SiO4 without any seed was 760 degrees C, while this temperature for the specimen containing 4 wt.% seed was 700 degrees C. (c) 2006 Elsevier Ltd. All rights reserved.