The material IMPEX consists of graphite matrices impregnated with salts and is used as a reactive bed in thermochemical transformers. A recently proposed thermodynamic method is used to investigate modifications induced in the texture of the matrices by the impregnation of salts. We take the experimental data obtained from low-temperature nitrogen adsorption into account in the fractal analysis, where the surface fractal dimensions are measured. In the first part, the nonimpregnated matrices are analyzed and compared with the precursor of the graphite materials. Compression of the matrix affects the specific surface area and the pore volume, but not the fractal dimension. In the second part, it is shown that the impregnation process leads to the defractalization of the surface of the matrix. From the experimental results, we have determined the distribution Of the salts.