This manuscript describes the use of a novel water-soluble photosensitive -cyclodextrin modified coumarin (-CD-C) to disperse carbon nanotubes (CNTs) in water. First, using epichlorohydrin as the bridged unit, water-soluble -cyclodextrin (-CD) was introduced to modify 7-hydroxy-4-methylcoumarin and prepare -CD-C. -CD-C was characterized with hydrogen nuclear magnetic resonance spectra (H-1-NMR) and High pressure liquid chromatography-mass spectrometry. The photodimerization experiment showed that -CD-C could photodimerize upon 365 nm irradiation, and then photo-de-crosslink upon the subsequent 254 nm irradiation. Next, -CD-C was used to disperse CNTs in water. Transmission electron microscope and scanning electron microscope demonstrated that -CD-C effectively adsorbed onto the surface of CNTs. The -CD-C is an efficient dispersant for CNTs. (c) 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2588-2593, 2013