An investigation was performed to prepare spherical cobalt powder with about particle size of 400mm from aqueous cobalt hydroxide slurry under hydrothermal reduction condition using palladiom chloride as acatalyst. The reduction kinetics was in good agreement with a surface reaction core model equation, and the activation energy obtainded from Arrhenius plots was 55.6 KJ/mol at the remperature range of 145~195oC. Additionally, the study showed that the cobalt reduction rate is proportinal to the initial hydrogen pressure with a reaction order of n=0.63, which corresponds to the gas chemisorption reaction type.