A series of multifunctional dye molecules with different relative positions of electron-accepting group, (E)-N-methyl-N-4-[2-(4-N-methyl-N-hexadecylaminophenyl) ethenyl]-2-quinolinium iodide (MHQ-2), (E)-N-methyl-4-[2-(4-N-methyl-N-hexadecylaminophenyl)ethenyl]-4-quinolinium iodide (MHQ-4) and (E)-N-methyl-4-[2-(4-N-methyl-N-hexadecylaminophenyl)ethenyl]-6-quinolin ium iodide (MHQ-6) were synthesized. These amphiphilic dye molecules were successfully transferred onto ITO electrode or quartz by Langmuir-Blodgett (LB) technique. The second-harmonic generation (SHG) and photoelectric conversion (PEC) properties of their monolayers were studied under identical conditions. The sequence of chi((2)) and the photocurrent external quantum yield under the same conditions is MHQ-4 > MHQ-2 > MHQ-6, implying that the relative position of acceptor plays an important role in SHG and PEC properties.