The drawback of some organic pesticides is their low water solubility. Cyclodextrins are used as agents for improving pesticides water solubility. However, the stabilization of the crystalline lattice can reduces to a large extent the solubility of cyclodextrins, especially b-cyclodextrin. Here, searching for the water soluble b-cyclodextrin derivatives, a set of new ''host'' compounds were prepared by the reaction of b-cyclodextrin with methyl epoxycinnamate. The reactants ratio was varied in to study the substitution degree of the obtained derivatives. The structure was determined by the 1 H-NMR and FT IR spectra. The average degree of substitution was determined by integration of the corresponding NMR signals and by elemental analysis. The solubility of four selected pesticides: dimethoate, simazine, linuron and thiram, in water with and without addition of the new modified b-cyclodextrin was measured by ultraviolet spectrophotometry. Our results showed that the modified b-cyclodextrins significantly improve solubility of pesticides.