Thermal decomposition of perfluoro(dimethylaminoacetic) acidalkalisalts was carried out at 220–310°C. A potassium salt gave CF3NCF2 as the principal product in moderate yield, together with CF3NCFCF3 and (CF3)2NCFCF2. Sodium and lithium salts gave (CF3)2NCFCFN(CF3)2 and (CF3)2NCF2C(O)X (X=F, OH) as the main products.