The isothermal kinetics of nicotine desorption from silicon dioxide (SiO2) was investigated. The isothermal thermogravimetric curves of nicotine at temperatures of 115 degrees C, 130 degrees C and 152 degrees C were recorded. The kinetic parameters (E-a, lnA) of desorption of nicotine were calculated using various methods (stationary point, model constants and differential isoconversion method). By applying the "model-fitting" method, it was found that the kinetic model of nicotine desorption from silicon dioxide was a phase boundary controlled reaction (contracting volume). The values of the kinetic parameters, E-a,E-alpha and lnA(alpha), complexly change with changing degree of desorption and a compensation effect exists. A new mechanism of activation for the desorption of the absorbed molecules of nicotine was suggested in agreement with model of selective energy transfer. (C) 2010 Elsevier B.V. All rights reserved.