We report new experimental data of heat capacity of two primary amines, namely 1-pentylamine and 1-hexylamine over wide ranges of pressure [0.1-60 (MPa)] and temperature [303.15-403.15 (K)]. The experimental behaviour of the heat capacity versus temperature and pressure is analyzed. An attempt to rationalize this behaviour is performed through a two-state association model (TSAM), which allows expressing the specific effect due to association at molecular level. It appears that the heat capacity trend versus temperature is clearly governed by auto-association between amines molecules. The physical meaningful of the (TSAM) model parameters highlights the capability of this approach to capture the heat capacity behavior of the amines. (C) 2012 Elsevier Ltd. All rights reserved.