The photochemical reaction of diphenyl ketone and isopropanol was investigated in homogeneous solution, anionic AOT-water-isopropanol and cationic CTAB-hexanol-water-isopropanol lamellar liquid crystals (LLC). X-ray diffraction (XRD) and IR spectra identified that same product, benzopinacol, was obtained from these different systems. However, the shape and size of particles are different: granular for homogeneous solution, irregular flakelike for CTAB LLC and thin, needlelike for AOT LLC systems. The average diameter (D) of the particles formed in three systems followed the sequence: D(solution) > D(CTAB LLC) > D(AOT LLC). The growth rate of particles was enhanced by increasing the incident light intensity, while the largest average diameter increased with decreasing light intensity. Comparing the average diameters of the particles formed in AOT LLC under different intensity of incident light, D(weak light)> D(moderate light)> D(strong light) was obtained.