Thermal analyses were used to study the sorbate/framework and sorbate/sorbate interaction on siliceous MFI type zeolite. Alkanes, aromatics, alkyl alcohols, multivalue hydroxyl alcohols, alkylamines, organic acids, acetaldehyde, ethyl ether, acetone, and ethyl acetate were investigated as the adsorbate. The adsorption and desorption behavior of high silica MFI type zeolite is greatly influenced by the presence of framework aluminum, cations, and silanol defects. There is a perfect Si-O-Si micropore surface without cations and silanol defects in the high hydrophobic zeolite silicalite. The essential host/guest interaction can be clearly studied by the thermal desorption behavior from silicalite. A general hydrophobic/organophilic property of 27 organic compounds with different functional groups on silicalite has been compared in terms of the affinity index A(T) determined by DTG. The physical meaning of the A(T) value, and the nature of the host/guest interaction are discussed. Silicalite has a strong affinity for some organic compounds with high polarity and is usually phobic to organics with hydroxyl groups. The special sorbate/framework and sorbate/sorbate interactions for certain organics can be identified from the double peaks in the DTG curves and thermal effects in the DTA curves. The formation of the double-molecule complexes of p-xylene, toluene, phenol, ethylene glycol, and ethylamine in silicalite is revealed.