Zerovalent samarium complexes with 1,3,5-tri-tert-butylbenzene were obtained by low temperature codeposition of metal and ligand vapours on the cold (77 K) surface under vacuum. The formation of two complexes was stated. The kinetics of thermal decomposition of complex with characteristic band at 967 cm(-1) was investigated. It was shown that the retarded kinetics takes place. An effective activation energy was calculated from the initial rates. Its value is 8 kJ/mol. which is typical for diffusion controlled reaction.