Novel poly(ester-ether-ester)s copolymers (PEED) were synthesized according to a 2-step procedure and studied for chemical structure, solubility and thermal properties. The introduction of oligoether sequences into polyester chain resulted in an increase in their solubility in water. Crystalli-zable poly(ethylene glycol) moieties (molecular mass 1000) contributed into an increase in degree of the crystallinity of the PEED hard segments. Possibility of tailoring PEED's structure based on biocompatible oligoethers and oligoesters allows to control their properties as biocompatible and biodegradable polymers for medical applications.