Thermal characteristics of the molybdates of magnesium (MgMoO4· 2H2O), manganese (MnMoO4· 1.5H2O) and silver (Ag2MoO4) have been studied by DTA and TG techniques. The thermal curves of MgMoO4· 2H2O show two endothermic changes at 195° and 390° followed by an exothermic change at 420°C. The endothermic changes represent the stepwise dehydration of MgMoO4· 2H2O to MgMoO4· H2O and from MgMoO4· H2O to MgMoO4. X-ray diffraction and IR studies, however, reveal that magnesium molybdate does not undergo any type of decomposition up to 900° and the exo-peak at 420° is clearly due to cryst