Mesoporous silicas MCM-41 and SBA-15 were studied using the quasi-equilibrated temperature-programmed desorption and adsorption (QE-TPDA) of n-nonane and 1-butanol The QE-TPDA profiles of n-nonane containing one desorption maximum were typical for the mesoporous materials The pore size distributions from the thermodesorption data were similar to those calculated from N-2 adsorption isotherms The QE-TPDA profiles of 1-butanol exhibited low temperature maxima (below 70 degrees C) resulting from desorption of the adsorbate filling the mesopores and high temperature maxima (at ca 100 degrees C) attributed to desorption of the molecules specifically adsorbed on the hydrogen-bonded silanols These findings were confirmed by IR measurements Hydrothermal treatment of MCM-41 resulted in increase of the H-bonded silanol concentration while for SBA-15 an Inverse effect was observed (C) 2010 Elsevier B V All rights reserved