Résumé : Conformational equilibrium of bromo‐ and chlorocyclohexane is studied in a series of solvents by infra‐red spectroscopy. Infra‐red spectra of bromo‐, chloro‐ and hydroxycyclohexane recorded for films of pure liquids at different temperatures yield values for the energy difference between equatorial and axial conformers of these compounds. Axial conformation of bromocyclohexane was shown to be present also in the gas phase. Infra‐red spectra of bromo and chlorocycloheptanes are analysed in the (C‐X) stretching region. Their conformations are discussed. Copyright © 1960 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim