The TGA curve of KH2PO4 show two main loss events: since it is an anhydrous material, the moisture loss is not seen and the first step at 200°C should be associated to crystallization water loss. The second step at 300°C corresponds to polycondensation, concomitant with structural water loss. The residual mass (89%) regards to KPO3 formation is consistent to the theoretical (87%) (Fig. ):