Molecular dynamics calculations were carried out in order to investigate the interfacial properties of the two-phase coexistence state of the triethylamine (TEA) and water mixture, which is known to have a lower critical soluble temperature. Two kinds of initial configuration were adopted. One was a two-phase coexistence state and the other was a random mixed state of TEA and water molecules. After an equilibration calculation of several nanoseconds, the density profiles converged to the same equilibrated two-phase coexistence state. In the equilibrated state, anisotropic orientations were observed for both molecules, which makes an electrostatic potential gap between these phases. (c) 2007 Elsevier B.V. All rights reserved.