Stable Nafion-Au colloids were immobilized on a glassy carbon electrode (GCE) for detection of beta-agonist clenbuterol by electroanalysis. The Au colloids were prepared by a one-step electrodeposition onto GCE, with obvious electrocatalytic activity present The negatively charged Nation film was an efficient barrier to negatively charged interfering compounds, resulting in accumulation of positively charged clenbuterol at the Nafion film The electrochemical characters of the electrode during various modified steps in a redox probe system of K-4[Fe(CN)(6)]/K-3[Fe(CN)(6)] were confirmed by cyclic voltammetry (CV) and AC-impedance In Britton-Robinson (B-R) buffer solution (pH = 2 0) and the potential range of-0 2 to 1 2 V, the Nafion-Au colloid modified electrode, compared to a bare GCE, exhibits obvious electrocatalytic activity towards the redox of clenbuterol by greatly enhancing the peak current with a linear calibration curve nom 80 x 10(-7) to 1.0 x 10(-5) mol/L and a detection limit of (10 x 10(-7) mol/L) (R = 0 996) The modified electrode shows high sensitivity, selectivity and reproducibility The recovery for detecting clenbuterol (similar to 10(-6) mol/L) in human serum is up to 98 19% (C) 2010 Elsevier Ltd All rights reserved