An NADH biosensor based on MWCNTs-Pd nanoparticles and polymerized 3,4-ethylenedioxypyrrole (PEDOP) was developed and characterized. PEDOP/MWCNTs-Pd/GCE was prepared quickly and simply and showed improved sensitivity to NADH. Comparable results were obtained by cyclic voltammetric (CV) and amperometric methods for NADH determination. The amperometric method gave short response times, and linear regression was observed at concentrations below 1.0 mM. The proposed NADH biosensor exhibited a wide linear response range of 1 mu M-13 mM during amperometric testing using an applied potential of 0.42 V, with a low detection limit of 0.18 mu M (S/N = 3). The sensor demonstrated fast responses and good stability. (C) 2011 Elsevier Ltd. All rights reserved.