Simultaneous constant-rate thermogravimetry-difference thermal analysis (TG-DTA) and thermogravimetry-mass spectrometry (TG-MS) of scandium hydrogenphosphite Sc-2((HPO3)-O-III)(3) (space group P6(3)/m) were conducted under inert conditions in flowing argon up to 1300 degrees C. The first significant mass loss step detected between 700 degrees C and 800 degrees C is mainly caused by the release of hydrogen resulting in the formation of optical transparent, red nano crystalline agglomerates. Further heating leads to disproportionation into phosphorus vapor and phosphates, namely (ScPO4)-O-V (space group I4(1)/amd) and Sc((PO3)-O-V)(3) (space group Cc). (C) 2012 Elsevier B.V. All rights reserved.