Hybrid Langmuir–Blodgett films consisting of sodium montmorillonite (a smectite clay) and nonamphiphilic cationic metal complexes [tris(4,7-diphenyl-1,10-phenanthroline)M]perchlorate (M=Mn, Co, Ni, Cu and Zn) have been fabricated. Optical second-harmonic generation (SHG) from the films was observed by employing a repetitive pulsed Nd:YAG laser operated at the wavelength of 1064nm. The SHG signal intensities were found to correlate with the absorbance of the films at the wavelength of the second harmonic light (532nm).