The activation energies and reaction orders of the thermal decompositions of three ammonium molybdates, (NH4)(6)Mo7O24. 4H(2)O, (NH4)(4)Mo5O17 and (NH4)(2)Mo4O13, were calculated according to Kissinger's method from the DSC measurements of their mixture in air at different heating rates. The activation energies were estimated to be 80.84, 144.83 and 150.48 kJ mol(-1), respectively, and the reaction orders one. The reason why the mixture of ammonium molybdates was used in the DSC measurements and the accuracy of the resulting kinetic parameters were also discussed.