Partial thermal decomposition of aluminum chloride hexahydrate was carried out in a rotary glass tube at temperatures of 230-260 degreesC. The decomposition solid product was dissolved in water to produce a ploy(aluminum chloride) (PAC) solution. The effects of the decomposition temperature, the rotation speed of the tube, and the feed rate of aluminum chloride hexahydrate on the properties and morphology of the basic chloride resulting from the decomposition were investigated. The basicity of the PAC obtained by dissolving the decomposition solid product in water was related to the extent of decomposition by the linear equation Y = 2.025 + 1.063X, where Y is the basicity (%) and X is the extent of decomposition (%). The PAC solution prepared by the present method showed a flocculation capacity comparable to that of an existing PAC made from aluminum hydroxide and hydrochloric acid.