We have investigated the degradation mechanism of Ba(DPM)(2), which has been stored in a desiccator for extended periods using thermogravimetry, FTIR and mass spectroscopy. TG analysis shows that the aged sample loses the initial weight significantly at relatively low temperatures, the rate of weight loss decreases above 380 degrees C, and large amounts of residue remain at 550 degrees C. FTIR and mass spectroscopy show that Ba(DPM)(2) is easily attacked by CO2 and H2O in air, which results in the dissociation of chemical bonds between the Ba ion and the ligand at low temperatures. This eventually enhances the oligomerization of Ba(DPM)(2) and the formation of carbonates that exhibit low volatility and unstable thermal properties.