The article describes the thermal behaviour of compounds with general formulae R1R2NCXCOOK (R=H, CH3; X=O,S). The decomposition of oxamates is very complicated with formation of cyanates, cyanides, oxalates and carbonates, the thiooxamates mainly form KOCN, R2S and CO. The E-a for the decomposition of oxamates is higher than that for the thiooxamates and occurs at higher temperatures. The influence of the crystal structure and the different processes on the E-a values are discussed.