Abstract: The explosive increase of information has created a great demand for higher densities of information storage. We describe the preparation of a thin film of the organic molecule 4'-cyano-2,6-dimethyl-4-hydroxy azobenzene by a self-assembly method. By applying a pulsed voltage between a scanning tunneling microscope tip and the substrate we realized ultrahigh density data storage on this organic film, and recorded information dots 1.8 nm in diameter. The mechanism of the recording is also analyzed.