Poly(2-hydroxyethyl methacrylate) (PHEMA) functionalized with chloroacetate groups was obtained by reaction of PHEMA with chloroacetyl chloride using the 5% lithium chloride/N,N-dimethylacetamide system as solvent and pyridine as catalyst. The coupling of bioactive carboxylic acid (1-naphthylacetic acid) to PHEMA functionalized with chloroacetate groups was carried out by reaction with its the potassium salt. The structures of chloroacetylated PHEMA and PHEMA-1-naphthylacetic acid adducts were determined by means FTIR, H-1-NMR and C-13-NMR spectra. The degree of substitution was calculated from the chloride content and ranged from 13.4 to 98.1 mol% depending on the ratio of chloroacetyl chloride to PHEMA. The hydrolysis in the heterogeneous phase of PHEMA-1-naphthylacetic acid adducts showed that the release of the bioactive compound from tablets is dependent on hydrophilic character of adduct as well as on pH value of the medium.