The LB films of asymmetrically substituted 1,4-di(hydroxyethoxy)-9,10,16,17,23,24-hexapentyloxyphthalocyanine have been fabricated at different surface-pressures, The molecular packing of the films has been characterized by polarized UV-vis. absorption spectroscopy and low angle X-ray diffraction methods. The results show that the films have well-ordered structure and the molecular packing within the films is dependent on the him-deposition conditions such as surface-pressure. The gas-sensing behavior of the films to NO2 gas has been investigated by conductance measurements. It is indicated that the films deposited at lower surface-pressure show larger and faster response and recovery kinetics.