Based on the data of the gas electron diffraction/mass spectrometry (GED/MS) experiment, the composition of the vapor over rhenium tetrafluoride at T = 471 K was established, and it was found that species of the Re2F8is present in the gas phase. The geometric structure of the Re2F8molecule corresponding to D4hsymmetry was found, and the following geometric parameters of the rh1configuration were determined: rh1(Re-Re) = 2.264(5) Å, rh1(Re-F) = 1.846(4) Å, α(Re-Re-F) = 99.7(0.2)°, φ(F-Re-Re-F) = 2.4 (3.6)°. Calculations by the self-consistent field in full active space approximation showed that for Re2F8, the wave function of the1A1gground electronic state can be described by the single closed-shell determinant. For that reason, the DFT method was used for a structural study of Re2X8molecules. The description of the nature of the Re-Re bond was performed in the framework of Atom in Molecules and Natural Bond Orbital analysis. The difference in the experimental values of r(Re-Re) in the free Re2F8molecule and the [Re2F8]2−dianion in the crystal corresponds to the concept of a triple σ2π4(ReIV-ReIV) bond and a quadruple σ2π4δ2(ReIII-ReIII) bond, respectively, which are formed between rhenium atoms due to the interaction of d-atomic orbitals. The enthalpy of dissociation of the Re2F8molecular form in two monomers ReF4(ΔdissH°(298) = 109.9 kcal/mol) and the bond energies E(Re-Re) and E(Re-X) in the series Re2F8→Re2Cl8→Re2Br8molecules were estimated. It is shown that the Re-Re bond energy weakly depends on the nature of the halogen, while the symmetry of the Re2Br8(D4d) geometric configuration differs from the symmetry of the Re2F8and Re2Cl8(D4h) molecules.