Thermal stability of some representatives of dimer chlorine acetate derivative of rhenium(III) was studied. The main feature of this compound is the existence of binuclear Re2 6 + fragment in a neutral molecule. In our previous works it was shown that Re2(CH3COO)2Cl4·2H2O enters the reaction with organic bases with following substitution of water molecules in axial positions. Analysis of thermograms of Re2(CH3COO)2Cl4·2H2O has shown existence of two endothermic effects at temperatures 195ºC and 420ºC. First endothermic effect at 195ºC on thermal heating curve may be explained by elimination of two molecules of water. We demonstrated, that the complete elimination of water may be reached at isothermal heating during 2 hours. We showed also, that the waterless cluster compound Re2(CH3COO)2Cl4 had thermal stability up to 300ºC. Under heating up to 200-250ºC the formation of volatile trans-Re2(CH3COO)2Cl4 , with yield of 80-90 %, per Rhenium waz registrated. Under isothermal conditions less than 2 hours the dehydration of the substance took place although not complete. Together with the formation of the volatile compound the reaction between a residue and not yet eliminated substituent occurred and led to the formation of hydroxy compounds. These compounds decomposed under second effect. Decomposition of Re2(CH3COO)2Cl4·2H2O may occur by different ways : 1) Under heating up to 160-180ºC during 2 hours two molecules of water were completely deleted and under further heating up to 200-250ºC the formation of volatile trans - Re2(CH3COO)2Cl4 took place; 2) heating without isothermal endurance at 160-180ºC led to not complete decomposition of the substance, and the formation of oxychloride took place. The value of activation energy at 195ºC - E = -133 kilojoule/mol of a limiting stage of elimination was calculated.