Temperature programmed desorption mass spectrometry (TPD-MS) and thermal gravimetry (TG) were utilized for the study of the
thermal dehydration and decomposition of copper selenate pentahydrate (CuSeO4·5H2O). From the two techniques we suggest that the dehydration is a 3-step process reaching completion at 300 °C. The decomposition
process however, is far more complicated consisting of several successive steps occurring between 480 and 900 °C. Initiated
with the emission of oxygen, the decomposition of the anhydrous salt continues with SeO2 emission via several unstable intermediates up to the conversion of the remaining copper monoxide into dicopper monoxide
accompanied by oxygen emission.