The thermal decomposition behaviour of the manganese(II) complexes with glycine: Mn(gly)Cl2(H2O)2, Mn(gly)2Cl2, Mn(gly)Br2(H2O)2, Mn(gly)2Br2(H2O)2 was investigated by means of TG-DTG-DTA, Hi-Res-TA and DSC techniques. The evolved gas analysis was carried out by means of the coupled TG-FTIR system. Heating of the complexes results first in the release of water molecules. Next, the multi-stage decomposition process with degradation of glycine ligand occurs. Water, carbon dioxide and ammonia were detected in the gaseous products of the complexes decomposition. The temperature of NH3 evolution from the complexes is higher than from free glycine. The final residue in the air atmosphere is Mn2O3 which transforms into Mn3O4 at 930C. In a nitrogen atmosphere, the complexes decompose into MnO.