The thermal decomposition process of manganous carbonate was studied by means or DTA under atmosphere of N_2,CO_2,and air. An endothermic peak appeared at 378℃ and an exothermic peak between 580 and 800℃ in atmospheric air were not reported till now. This endothermic peak became smaller with decreasing pressure and dissappeared at 100 mmHg.[chemical formula]Only one endothermic peak on the DTA curve under atmosphere of CO_2,and N_2 was observed
