Abstract.Theoretical investigation has been performed on electron transport properties of NO2- three phenyl acetylene based molecules sandwiched between two external electrodes and one metal such as Cu, Ag and Au. Molecules bonded between two metal contacts form the simplest possible molecular devices. The charge transfer and bonding nature at the metal-molecule interface are illustrated from natural bond orbital analysis. The metal-sulfur bonds are found to be directional, and the charge transfer is localized along the bond.. The dependence of the molecular electronic structure of the metal–molecule complexes on the external electric field has been also studied. The electronic conduction has been analyzed from the change in the shape of molecular orbitals and the evolution of the HOMO– LUMO gap of the molecule-gold complexes under the influence of the electric filed. The results suggest that while the inclusion of Au scarcely affects the unoccupied molecular orbitals, the effect is more pronounced in the cases of Cu and Ag.