The anodic oxidation of hydrazine has been studied on a glassy carbon electrode by electrocatalytic effect of pyrogallol red as a homogenous mediator, using cyclic voltammetry, linear sweep voltarnmetry and chronoamperometry as diagnostic techniques. Using cyclic voltarnmetry study showed that, the catalytic current of the system depends on the concentration of hydrazine. The magnitude of the peak current for pyrogallol red increased sharply in the presence of hydrazine, and proportional to hydrazine concentration. The diffusion coefficient of hydrazine was also estimated using chronoamperometry. The chronoamperometry studies also were used to determine the catalytic rate constant for catalytic reaction of pyrogallol red with hydrazine. The experimental results showed that the peak current varied in the presence of different metal cations, but these effects were omitted in the presence of EDTA, while almost all of anions had no effect on the peak current of hydrazine. The proposed method was used for analysis of hydrazine in real samples. (c) 2005 Elsevier B.V. All rights reserved.