Photo-responsive monoolein cubic phases were developed by immobilizing hydrophobically modified poly (vinyl alcohol)-epoxypropoxy coumarin conjugate (HmPVA-EPC) in the water channels of the cubic phase. On the NMR spectrum of HmPVA-EPC, the molar ratio of PVA/decanoyl chloride (a hydrophobic anchor)/EPC was determined to be about 1:0.64:1.45. The interfacial activity of PVA-EPC conjugate was much lower than that of PVA, but the interfacial activity of HmPVA-EPC was as high as that of PVA. The critical micelle concentrations of HmPVA-EPC and PVA were about 0.005%. Under the ultraviolet (UV) irradiation ( = 254 nm), EPC residues of HmPVA were readily dimerized and the dimerization degree in 180 min was about 33%. The irradiation of UV light had no significant effect on the release of fluorescein isothiocyanate-dextran (a fluorescence marker) from cubic phase free of polymer and cubic phase incorporating HmPVA, but it suppressed the release from cubic phase incorporating HmPVA-EPC. The photo crosslinking of HmPVA-EPC in the water channels is believed to be responsible for the suppressed release. POLYM. ENG. SCI., 54:227-233, 2014. (c) 2013 Society of Plastics Engineers