The behavior of potassium carbonate was studied by thermal analysis near its melting point under 1 atm total pressure. Literature data are scant regarding the degree to which K2CO3 decomposes in sub- and pro-liquidus thermal environments, and reliable thermodynamic data are not available for the reaction K(2)CO(3)reversible arrow K2O + CO2 in the temperature range of interest. TGA and DTA analyses indicate that significant volatilization occurs below the melting point and the logarithm of the rate of volatilization is a linear function of 1/T above the melting point. The effect of CO2 partial pressure was highly significant in reducing, but not eliminating, volatilization near the melting point. Graphs of In[P-CO2 x weight loss rate] vs. (1/T) were linear, supporting a decomposition model rather than congruent volatilization. The melting point of K2CO3, as measured by DTA, is 905 degrees C in CO2 and 900 degrees C in N-2.