A poly(ether-ester-urethane) block copolymer based on poly(ε-caprolactone) and polyethylene glycol (PEGCL) was employed for the production of Doxorubicin loaded polymeric nanoparticles to be used as a drug delivery system. Nanoparticles were obtained by means of the nanoprecipitation/solvent evaporation technique, possessing a spherical shape and an average diameter of about 80 nm. The optimization of the formulation process led to high formulation yield and appreciable drug content. One of the main findings arising from the present study is represented by the protective activity played by nanoparticles in terms of preventing doxorubicin degradation in physiological conditions; moreover the observed time-delayed release of the drug was associated to PEGCL chemical structure.