Abstract: polymers having both crown ether moieties as cation binding sites and cinnamic acid ester moieties as photodimerizable pendant groups were prepared. On irradiation with UV light the cinnamic acid ester groups of the polymers caused dimerization in dilute solution without formation of any insoluble material. Irradiation was carried out in THF and THF-methanol (1:1 vol. ratio) in the absence and presence of cations as a template, respectively. The cation binding properties were investigated by means of the method of picrate salts extraction. The cation extractability of the photoreacted polymers was higher than that of the original polymers. Furthermore, the cation binding ability of the photoreacted polymers was less sensitive to temperature than that of the original polymers. The effect of the degree of photodimerization of the polymers, of the kind of cations used as a template during photodimerization of the polymers, and of the concentration of the template cation on the extractability of polymers were investigated in detail.