This paper describes the synthesis and modification of functional poly(ester-anhydride)s that have potential for a variety of applications in drug delivery. Functional poly(ester-anhydride)s with pendant allyl groups were synthesized by two step polycondensation of oligo(3-allyloxy-1,2-propylene succinate) terminated with carboxyl end groups (OSAGE) and one of diacids (DA): sebacic (SBA) or dodecanedicarboxylic acid (DDC). Poly(ester-anhydride)s with molecular weights with range of 3100-7300 Da and with varying degree of functionality were oxidized with m-chloroperbenzoic acid (MCPBA) to yield respective polymers with epoxy pendant groups. The OSAGE to DA ratio in the poly(ester-anhydride)s, polymer concentration in the reaction solution, excess of MCPBA and duration of the reaction, had influenced the conversion of allyl groups into glycidyl ones. For all types of poly(ester-anhydride)s conditions were set up in which 100% of epoxidation could be achieved. Completely oxidized poly(ester-anhydride)s were characterized by means of H-1 NMR spectroscopy and DSC technique. Their thermal and solubility characteristics were compared with characteristics of initial poly(ester-anhydride)s. Initial and oxidized polymers containing 80% of SBA or DDC were formulated into microspheres using O/W emulsion technique. The presence of epoxy groups at the surface of microspheres were confirmed by AIR IR spectroscopy. Microspheres obtained were subjected to hydrolytic degradation at 37 degrees C, in aqueous phosphate buffer solution of pH = 7.41 (PBS). (C) 2012 Elsevier Ltd. All rights reserved.