The infrared spectra (3200-30 cm Γ1 ) of the gas, amorphous and annealed solid and Raman spectra (3200-30 cm Γ1 ) of liquid and solid bromocyclohexane (c-C 6 H 11 Br) have been recorded. Variable temperature (Γ55 to Γ100 o C) studies of the infrared spectra (3200-400 cm Γ1 ) of bromocyclohexane (c-C 6 H 11 Br) dissolved in liquefied xenon have been carried out. From these data, the enthalpy difference has been determined to be 239 Β± 24 cm Γ1 (2.86 Β± 0.29 kJ mol Γ1 ), with the chair-equatorial conformer the most stable form. At ambient temperature, the abundance of the chair-axial conformer is 24% Β± 2. From MP2 ab initio calculations utilizing various basis sets with and without diffuse functions, the equatorial conformer is predicted to be more stable by 168 Β± 22 cm Γ1 from the four largest basis set calculations. However, the average from the corresponding B3LYP density functional theory calculations is 300 Β± 16 cm Γ1 which, considering the error, is consistent with the experimental value. By utilizing the previously reported microwave rotational constants for two isotopomers ( 79 Br, 81 Br) combined with the structural parameters predicted from the MP2(full)/6-311+G(d,p) calculations, adjusted r 0 structural parameters have been obtained. The determined heavy atom distances for the most stable chair-equatorial conformer in Γ
are r 0 (C 1 -C 7 , 8 ) = 1.532(3); r 0 (C 7 , 8 -C 13 , 14 ) = 1.539(3); r 0 (C 4 -C 13 , 14 ) = 1.524(3); and r 0 (C 4 -Br 6 ) = 1.966(5) and the angles in degrees: \C 1 C 7 , 8 C 13 , 14 = 111.3(5)Β°; \Br 6 C 4 C 13 , 14 = 109.8(5)Β°with the two dihedral angles \C 8 C 1 C 7 C 13 = 55.9(10)Β°and \C 14 C 4 C 13 C 7 = 57.7(10)Β°.For the axial form the major differences in distances are obtained for the r 0 (C 7,8 -C 13,14 ) = 1.531(3) and r 0 (C-Br) = 1.975(3) Γ
. These parameters are in good agreement with those reported earlier from microwave and electron diffraction studies where the CC and CH distances were all assumed to be equal. A few of the previously reported vibrational assignments have been corrected. The results of these spectroscopic and theoretical studies are discussed and compared to the corresponding results for some similar molecules.