This paper studies the detection of copper ions by using an iminodiacetatic acid (IDA) modified conducting copolymer electrode. The copolymer film comprising 3-methyl thiophene (3MT) and 3-thiophene acetic acid (3TA) was chosen as the selective metal cation sensing electrode. The carboxylic group of the copolymer was modified to produce IDA group for metal ion capture. The modified electrode was used for the electrochemical analysis of trace copper ions by square wave voltammetry (SWV) technique. The electrode was found to be highly selective to Cu2+ in the range of 0.1-10 mu M. The modified electrode offered an excellent way, with a high stability and reusability, for selective determination of Cu2+ in a solution of mixed metal ions. (C) 2009 Elsevier Ltd. All rights reserved.