The enhancement of metal-polymer adhesion via thin reactive electropolymer films of poly(2-allyl)phenylene oxide was studied using adhesive joint failure techniques. Thin (0.2-0.4 micron) films were formed on steel blocks using potentiostatic electrooxidation. Two blocks were cemented together to form adhesive joint specimens using an unsaturated polyester/styrene resin system. Adhesive joint specimens were also formed from both untreated blocks and treated blocks where the allyl functionality of the electropolymer was destroyed by heat crosslinking. Failure energies were then determined for joints with variable areas of adhesion using an impact-based technique, and the relationship of adhered area to measured failure energy was obtained for the three systems. The failure interface was examined by scanning electron microscopy. It was found that the poly(2-allyl)phenylene oxide-treated system gave the highest failure energies, followed by the untreated system. The electropolymer film system with pre-crosslinked allyl functionality produced the lowest failure energies. These results were related to the nature of the chemical interactions present at the interfaces, in accordance with the theories of adhesion proposed by Kinloch.