The electrocatalytic oxidation of hydrazine has been studied on glassy carbon modified by electrodeposition of quinizarine, using cyclic voltammetry and chronoamperometry techniques. It has been shown that the oxidation of hydrazine to nitrogen occurs at a potential where oxidation is not observed at the bare glassy carbon electrode. The apparent charge transfer rate constant and transfer coefficient for electron transfer between the electrode surface and immobilized quinizarine were calculated as 4.44 s(-1) and 0.66, respectively. The heterogenous rate constant for oxidation of hydrazine at the quinizarine modified electrode surface was also determined and found to be about 4.83 x 10(3) m(-1) s(-1). The diffusion coefficient of hydrazine was also estimated as 1.1 x 10(-1) cm(2) s(-1) for the experimental conditions, using chronoamperometry. (c) 2007 Elsevier Ltd. All rights reserved.