A new electrochemical method was proposed for the determination of thymine, which relied on the oxidation of thymine at a carbon ionic liquid electrode (CILE) in a pH 5.0 Britton-Robinson buffer solution. CILE was fabricated by using ionic liquid 1-(3-chloro-2-hydroxy-propyl)-3-methylimidazole acetate as the binder, which showed strong electrocatalytic ability to promote the oxidation of thymine. A single well-defined irreversible oxidation peak appeared with adsorption-controlled process and enhanced electrochemical response on the CILE, which was due to the presence of high conductive ionic liquid on the electrode. The reaction parameters of thymine were calculated with the electron transfer coefficient (alpha) as 0.27, the electron transfer number (n) as 1.23, the apparent heterogeneous electron transfer rate constant (k(s)) as 6.87 x 10(-6)s(-1) and the surface coverage (Gamma(T)) as 5.71 x 10(-8) mol cm(-2). Under the selected conditions the oxidation peak current was proportional to thymine concentration in the range from 3.0 to 3000.0 mu M with the detection limit as 0.54 mu M (3 sigma) by differential pulse voltammetry. The proposed method showed good selectivity to the thymine detection without the interferences of coexisting substances. (C) 2010 Elsevier Ltd. All rights reserved.