In this work we investigated the possibilities of the solvent free synthesis of Schiff base (azomethyne) from 17-methyltestosterone and o-aminophenol. The study of the binary mixtures of 17-methyltestosterone and o-aminophenol was achieved by DSC. TG-DSC, and FTIR. The isolated compounds and reaction product were studied by adiabatic bomb calorimetry in order to determine the heat of reaction. The DSC data reveal a simple eutectic followed by a chemical reaction in liquid phases. From the DSC data we calculated the enthalpy of decomposition of reaction product as (44.65 +/- 0.83) kJ . mol(-1). Schiff base formation by condensation reaction was highlighted by TG-DSC method and the structure of the solid product was confirmed by FTIR spectroscopy. The standard enthalpy of reaction was calculated from the standard molar enthalpy of formation of reactants and products. (C) 2011 Elsevier Ltd. All rights reserved.