Copper cyclo-tetraphosphate was synthesized from basic copper carbonate and phosphoric acid and then treated with the planetary mill for several minutes. The un-milled and milled samples were characterized by simultaneous thermogravimetry-differential thermal analyses, X-ray diffraction, and Fourier transform infrared spectroscopy. SEM images, particle size distribution, specific surface area, acidic properties of the materials were also used for the estimation. Furthermore, as their application, the adsorption ratio of trimethylamine was measured. The mechanochemical reforming of copper phosphates was clarified from the changes of some properties that were related with the refinement and cleavage of chemical bonding. (c) 2007 Elsevier B.V. All rights reserved.