Correlation of the molecular structure and utilizing measurements of the electrical conductivity, activation energy of conduction of 4, 4' bis(2-thenylideneamino)biphenyl (SB) and 4, 4' bis(thenyl-diphenylphosphinylmethyleneamino)biphenyl (OPSB) compounds have been carried out. The results of the activation energies, obtained from the electrical conductivity measurements, as well as the energy gaps calculated from ultraviolet (u.v.) and visible spectra in the solid state indicate that the investigated compounds behave like semiconducting materials. The delocalized pi-electrons in addition to the lone pairs of electrons on the nitrogen atoms of the two compounds as well as the donor effect of diphenylphosphinyl groups of OPSB compound were considered as the main sources participating in the conduction processes.