This paper studies on the analytical performance and characterization of a peptide modified biosensor towards detection of copper ions.The poly(3-thiopheneacetic acid) was chosen as the conducting polymer electrode.X-ray photoelectron spectroscopy (XPS) and ATR-IR spectroscopy were used to characterize the steps of the biosensor fabrication.The peptide (Gly-Gly-His) modified poly(3-thiopheneacetic acid) (PTAA) biosensor was used for the electrochemical analysis of copper ions by square wave voltammetry.The electrode was found to be highly selective to Cu2+ ions in the range of 20-0.02μM.Interference of this biosensor was investigated.The peptide modified biosensor offers an excellent way for the selective trace determination of metal ions in a solution and a high stability and a recyclable affinity.