The molar excess enthalpies of 1,2- and 1,3-propanediamine + 1 - or 2-propanol and 1,2- and 1,3-propanediol + 1- or 2-propaneamine have been determined at 298.15 K using a twin-microcalorimeter for a series of runs over the whole range of mole fractions. All excess enthalpies were large exothermic, in particular, the systems of amines + propanediols were more than -5 kJ mol(-1) at the minimum. Primary or secondary alcohols and an-tines showed systematically different enthalpic behaviors. Equilibrium constant K1 expressed in terms of mole fractions and standard enthalpy of the formation of a 1: 1 complex have been evaluated by ideal mixtures of momomeric molecules and their associated complexes. (c) 2006 Elsevier B.V. All rights reserved.