In the present study, existing analytical models developed to predict the thermal contact conductance for both aluminum/aluminum and aluminum/stainless steel surfaces in contact have been evaluated. The prediction of thermal contact conductance for these contacting pairs is difficult since a thin native oxide film generally occurs naturally on the aluminum materials. Therefore, one of the objectives of this study was to determine whether elastic or plastic thermal contact models could successfully predict both published and present experimental data for these commercially important alloys. A rigorous analytical analysis was conducted to check the validity of existing models (assuming either elastic or plastic deformation a priori) to predict the thermal contact conductance for nominally flat uncoated aluminum surfaces in contact under vacuum conditions. Both elastic and plastic deformation models were compared with new unpublished experimental data for nominally flat, roughened surfaces. NOMENCLATURE A Fraction of area in real contact Aa Apparent area a Contact spot radius (m) BJH Microscopic gap number b Flux tube radius (m) Cjn Microscopic constriction number E Young's Modulus (N/m2)