Hydrotalcite was synthesized by a homogeneous precipitation method utilizing urea hydrolysis. When the homogeneous aqueous solutions containing magnesium chloride, aluminum chloride, and urea were heated, hydrotalcite particles were obtained. Scanning electron micrographs revealed that the products were well-defined hydrotalcite particles. The particle sizes have been controlled from ca. 2 to 20 mum by the reaction temperature and the concentration of the reactants. The particle morphology of hydrotalcite was retained even after thermal decomposition, showing the possible application of the present well-defined hydrotalcite particles for the preparation of layered double hydroxide intercalation compounds by the reconstruction method.