The intercalation of phenol into p-[2-(2-hydroxyethyldimethylammonio)ethoxy]azobenzene–clay (montmorillonite, synthetic saponite and fluor-tetrasilicic mica) intercalation compounds induced by UV irradiation is reported. Phenol was intercalated into the interlayer spaces of the azo dye–fluor-tetrasilicic mica (the cation exchange capacity of fluor-tetrasilicic mica: 94 meq. per 100 g clay) and -montmorillonite (the cation exchange capacity of montmorillonite: 108 meq. per 100 g clay) by the reactions with neat phenol. Upon UV irradiation, the basal spacings of the products increased further and subsequent visible light irradiation resulted in the decrease in the basal spacings, indicating that the intercalation and deintercalation of phenol were induced by the photoirradiation. When saponite, whose cation exchange capacity is 71 meq. per 100 g clay, was used as the host, the intercalation of phenol to expand the interlayer space was not observed. Thus, the structures of the azo dye–clay intercalation compounds played an important role in the photoinduced intercalation of phenol.