Electrospinning is a method for the preparation of nanosized polymer fibers. Here, electrospinning is used to prepare a blend of a polyester, poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV), and a globular protein, bovine serum albumin (BSA). The electrospun blend film is compared with a solution-cast blend film and with single-component electrospun films made of PHBV and BSA. In the electrospun blend films, BSA manifests itself as flat ribbons and a fine network formed from fibers less than 50nm in diameter. The dissolution rate of BSA from the electrospun blended film is lower than from the solution-cast one. The films are characterized using scanning electron microscopy, differential scanning calorimetry, and contact-angle measurements. The obtained PHBV+BSA blend films have several emergent properties: a slow BSA dissolution rate, a fine BSA network, and unusual thermal behavior. Thus, the PHBV+BSA blend films introduce a new class of polymer-protein blends. (C) 2017 Wiley Periodicals, Inc.