In situ reduction kinetics of CoCl2-SiO2 gel to Co-SiO2 nanocomposite in the 800-950 degrees C range has been studied. The presence of nanosized metallic Co in the host matrix has been established from the X-ray diffraction patterns of the reduced gels. The metallic panicle size has been found to be 17 and 23 nm when reduced at 850 degrees and 950 degrees C, respectively. Nucleation and growth type of mechanism remain operative during the course of the reduction. The activation energy is found to be in the range of 55-61 kJ/mol.