Thermal behaviour of molybdic acid, H2MoO4 has been investigated by DSC and thermogravimetry. The results obtained from the study demonstrated that it decomposes at the temperature range of 373 to 973 K in two steps. In the 1st step the peak was obtained at 604 K (Range 547.7-641 K) which is associated with 8.4 mass losses and in the 2nd step the peak was obtained at 688 K where decomposition started at 657 K and was completed at 710.3 K is associated with 2.2 mass losses. The different phases of H2MoO4 have been characterized by IR spectroscopy and Magnetic susceptibility. Magnetic susceptibility, after the diamagnetic corrections suggests that all the samples are diamagnetic. This is because of the fact that the Mo+6 ions, present in these samples, contain no unpaired electron. The kinetic studies suggest that the kinetic data in the first transition follow the Ginstling-Brounshtein mechanism, while the second transition obeys the Mampel’s unimolecular law of random nucleation.