The separation of a mixture of C5–C9 n-paraffins was achieved by Inverse Gas Chromatography (IGC) by using boehmite; AlO(OH), in a packed column with short exposure times and temperatures; from 45 °C to 52 °C. The boehmite was characterized by XRD; ATG; SEM; IR spectroscopy and N2 adsorption. The material exhibited a low crystalline boehmite (AlOOH) structure and presented high hydration (pseudoboehmite). The reverse gas chromatography measurements showed that the elution temperatures of the C5–C9 n-paraffins were low compared with those obtained for other adsorbents. The differential heat of adsorption values ensures the satisfactory separation of the components in the C5–C9 mixture under suitable chromatographic conditions.