The present work deals with the investigation of the thermal properties of two volatile rhenium compounds Re-2(CO)(10) and Re(CO)(3)(C5H5). The thermal behaviour of Re(CO)(3)(C5H5) in the condensed phase is studied by means of thermogravimetry and differential scanning calorimetry. Thermal decomposition of the vapour of Re-2(CO)(10) and Re(CO)(3)(C5H5) is studied in vacuum and in the presence of hydrogen and water vapour by means of in situ high-temperature mass spectrometry. The routes of vapour decomposition on a heated surface are proposed. Using Knudsen's effusion method with mass spectrometric registration of the composition of the gas phase, and the flow method, temperature dependences of saturated vapour pressure were measured: thermodynamic parameters of the sublimation of complexes were calculated. For Re-2(CO)(10) we specified the data on the saturated vapour pressure using two independent methods within the temperature range below the phase transformations of the compound and the start of decomposition of complex vapour: Delta H-Tover(o) =(95.5 +/- 2.3) kJ . mol(-1). Delta S-Tover(o) = (188.3 +/- 7.0) J . mol(-1).K-1 (effusion method), Delta H-Tover(o) = (93.6 +/- 1.7) kJ . mol(-1).Delta.S-Tover(o) = (187.5 +/- 5.0) J . mol(-1) . K-1 (flow method). For Re(CO)(3)(C5H5) the thermodynamic characteristics were determined for the first time: Delta H-Tover(o) = (85.2 +/- 1.0) kJ . mol(-1), Delta S-Tover(o) = (173.6 +/- 2.7) J . mol(-1) . K-1 (flow method). (C) 2011 Elsevier Ltd. All rights reserved.