A series of pure and mixed Mn and Cu oxides were prepared by calcination of MnCO3 and CuCO3. Cu(OH)(2) at different temperatures, (250, 500, 750 and 1000 degrees C) for 4 h in air. Pyrolyses of pure and mixed solid salts were investigated using the thermal analysis (DTA and TG) technique in a flow of air. Also, the calcined samples were analyzed for different species using X-ray diffraction (XRD). A solid-state reaction model accounting for the Mn oxide-Cu oxide interaction in mixed systems is discussed. The catalytic activity of the thermal products of pure and mixed solids was tested in H2O2 decomposition as a model reaction.