The binary solid mixtures of n-paraffins, C₂₂-C₂₄, with different molar ratios of 96:4, 3:1, 2:1, 1:4, 1:5, and 1:10 have been studied by FTIR spectroscopy, X-ray diffraction and differential scanning calorimetry (DSC). Temperature-dependent studies of Davydov splitting value, Δν_1,2, of in-phase CH₂ rocking vibrations have been shown to allow the determination of ΔT_rot temperature intervals, where rotation-crystalline states, characterized by different types of molecular motion, exist. The comparison of the ΔT_rot values obtained by FTIR and DSC methods with the corresponding temperature-dependent X-ray powder diffraction data has shown their good agreement.