This work deals with the coupling of nalidixic acid (NAL) to poly (vinyl alcohol) (PVAL) functionalized with chloroacetate groups by reaction with its potassium salt. The structure of the resulting adducts was determined by means of H-1 and C-13 NMR spectroscopy. The obtained results show the reaction to occur in a quantitative way. The hydrolysis in the heterogeneous phase of PVAL-NAL adducts showed that the release of the bioactive compound is dependent on the hydrophilic character of the adduct as well as on the pH value of the medium.