Rapeseed oil-based polyols (1%) and NaCl were added to an oligoester made of citric acid with 1,6-hexanediol to produce aliph. elastomeric polyester foams. The polyols were prepd. by epoxidation of rapeseed oil and following opening the epoxy ring with (HOCH(2))(2) under microwave irradn. in presence of H(2)SO(4). The foams showed an improved tensile strength an d decreased elongation at break. No significant change in swelling properties of the polyesters was obsd.