The non-isothermal behavior Of xV(2)O(5).40CaO.(60-x)P2O5 (10 less than or equal to x less than or equal to 30) glasses has been studied using a differential scanning calorimeter. The variation in the glass transition temperature for different compositions has been interpreted in terms of the variation in the molar volume of oxygen ion in the glasses. The Kissinger method was used for the calculation of the activation energy for the glass transition. The activation energy decreases with an increase in V2O5 content. The variation of the excess heat capacity at glass transition with V2O5 content has been interpreted in terms of the variation in the fragility of the glasses. (C) 2003 Elsevier B.V. All rights reserved.