A　polypyrrole/palladium　composite　film　was　prepared　on　a　glassy　carbon　electrode　by　the　electrochemical　deposition　method.　The　palladium　particles　were　uniformly　dispersed　on　a　polypyrrole　film　that　was　previously　electrodeposited　on　a　glassy　carbon　electrode.　By　controlling　the　polymerization　process　of　pyrrole,　a　highly　porous　polypyrrole　film　was　obtained;　this　kind　of　structure　provided　more　surface　areas　for　depositing　palladium　particles.　The　sizes　of　Pd　particles　deposited　on　the　porous　polypyrrole　film　are　about　15-30　nm.　The　X-ray　photoelectron　spectroscopy　results　showed　there　was　strong　interaction　between　polypyrrole　film　and　palladium　particles.　This　modified　electrode　showed　excellent　current　efficiency　(49.5%)　for　electrochemical　hydrogenation　of　4-chlorophenol　and　the　phenol　was　the　sole　product.　The　potential　effect　on　the　dechlorination　process　was　also　investigated.