We report on the temperature dependence of optical second harmonic generation from a thin indium tin oxide (ITO)‐coated glass substrate (commonly used as a transparent electrode), from a polymer layer on ITO, and from an antimony tin oxide (ATO) coating. We have found that when thin isotropic polymer films are deposited on the ITO‐coated surface, the resulting second harmonic intensity is larger than the second harmonic intensity from ITO or polymer separately. We discuss how the ITO interface may act to induce polar order in the polymer and consider how interfacial second harmonic sources contribute to electric‐field‐induced second harmonic studies of dye‐doped polymers in which ITO is used as a transparent electrode. ©1995 American Institute of Physics.