The alumina-dye composites were prepared by treating the basic alumina with the water solutions of Reactive Red 120 (RR 120) and Reactive Blue 15 (RB 15) dyes. The bands of low intensities in the 1400-1600 cm(-1) region and at 783 cm(-1) in the IR spectra of these composites point out that the dye species is bound weakly to the surface. In the case of mechanochemical adsorption of dye molecules, the asymmetric and symmetric S(=O)(2) and the S-O-C stretching bands together with the vibrations of aromatic ring revealed that dye types under dry conditions interacted effectively with alumina surface. After the heating of the alumina dye complexes in the temperature range 150-350A degrees C, the intensities of the IR and XRD peaks for adsorbed types decreased. The endothermic peaks over 200A degrees C and the bigger total mass losses for the alumina-dye composites can be ascribed to the decomposition of dye species retained by the alumina surface. The mass losses on TG curves of the alumina-dye complexes up to similar to 800A degrees C exhibit the removal of black residues occurred by decomposition of first adsorbed products. The thermal analysis data also point out that the water molecules bonded strongly to the alumina surface and dye types compete to accommodate at the surface active sites.