Nickel pyrophosphate was prepared and then treated with the planetary mill for several minutes. The milled samples were characterized by inductively coupled plasma, differential thermal analyses, X-ray diffraction, and Fourier transform infrared spectroscopy. SEM images, particle size distribution, specific surface area, surface acid strength, and amount of acidic sites of the materials were also used for the estimation of samples. Furthermore, the catalytic activity of the phosphates was calculated on the decomposition reaction of trifluoromethane. The mechanochemical reforming of nickel pyrophosphate was clarified from the changes of some properties that were related with the catalysis. (c) 2005 Elsevier B.V. All rights reserved.