Dielectric polarization phenomena of two-dimensional surface organic monolayer comprised of rod-like polar molecules on a water surface have been investigated. It was experimentally shown that Maxwell displacement current (MDC) measurement technique coupled with optical second harmonic generation (SHG) measurement was effective for the study of surface polarization, i.e., spontaneous polarization and nonlinear polarization. Theoretically, it was shown that surface polarization is expressed using orientational order parameters S-n defined by Legendre polynomials of orientational angle theta, P-n(cos theta) (n = 1, 2, and 3). As an example of MDC-SHG experiments, the results on mesogenic liquid crystal (LC) monolayers of 4'-n-octyl-4-cyanobiphenyl (8CB) were shown and discussed in terms of surface polarization. Finally, the effect of surface polarization on the textures of two-dimensional monolayers was discussed. (c) 2005 Elsevier B.V. All rights reserved.