Subambient HPLC allows the separation of thermally labile or unstable compounds that cannot be eluted at room temperature. The first successful separation of Fe(III) tris-1,1,1-trifluoroacetylacetonate is reported at −30°C. General observations of the behavior of normal-phase HPLC at reduced temperature, with regard to k′ and column efficiency, are reported both for metal complexes and aromatic hydrocarbons. The technique is applicable to other species that are thermally unstable and also provides a means of increasing the retention of poorly retained compounds.