Trans --> cis photoisomerization of an azobenzene derivative in a Langmuir-Blodgett (LB) film was induced by successive linearly polarized UV illuminations along different directions. Polarized UV-visible spectroscopy was used to determine that the isomerization occurred with the highest probability along the polarization direction. After UV irradiation, the application of cathodic potential reduced the cis isomer to hydrazobenzene, which is not only thermally stable but, more importantly, insensitive to the actinic light for the trans-cis photoisomerization. By combining the electrochemical method, the utilization of successive polarized UV irradiations allows for the possibility of obtaining the composition of the hydrazobenzene molecules with selective orientations in the surface plane of the film. A new type of in-plane polarized interconversion system was developed by the photoelectrochemical hybrid technique.