A novel imidazolium-based ionic liquid (IL), covalently bound to catechol (CA) groups by carbodiimide-mediated coupling reactions, was synthesized and used as the electrochemical sensing probe for dihydronicotinamide adenine dinucleotide (NADH). The thin layer of the CA-functionalized IL (IL-CA) at the screen-printed carbon electrode (SPCE) exhibited a stable redox couple originating from the catechol/quinone at the terminus. The redox-active film-modified electrode exhibited high and persistent electrocatalytic activity at 0.32V for the oxidation of NADH in pH 7.0 buffer solutions, while the oxidation reaction occurred at 0.75V at the bare electrode. Moreover, the modified electrode also showed free of interference from ascorbic acid (AA) and uric acid (UA). Flow-injection amperometry was performed for 1-1000 mu M of NADH under optimized conditions, and a linear calibration plot with a slope of 0.0078 mu A/mu M was obtained. The detection limit (S/N = 3) was 0.4 mu M. (C) 2012 Elsevier Ltd. All rights reserved.