A chemically modified carbon ceramic composite electrode (CCE) containing Dichloro{(8, 9-dimethyl-dipyridio [2,3-a:2',3'-c] phenazine-kappa(2)-N,N') bis(triphenylphosphine-kappa-P)} ruthenium (II) complex which synthesized newly was constructed by the sol-gel technique. Electrochemical behavior and stability of modified CCE were investigated by cyclic voltammetry. The electrocatalytic activity of CCE was investigated and showed a good effect for oxidation of hydrazine in phosphate buffer solution (PBS). A linear concentration range of 6 mu M to 1.2 mM of hydrazine with an experimental detection limit of 1 mu M of hydrazine was obtained. The diffusion coefficient of hydrazine and its catalytic rate constant for electrocatalytic reaction along with the apparent electron transfer rate constant (k(s)) and transfer coefficient (alpha) were also determined. The modified carbon ceramic electrode doped with this new Ru-complex showed good reproducibility, short response time (t < 2 s), remarkable long-term stability (>3 month) and especially good surface renewability by simple mechanical polishing. The results showed that this electrode could be used as an electrochemical sensor for determination of hydrazine in real water samples used in Fars Power Plant Station, including its heat recovery steam generator (HRSG) water (at different operational condition), cooling system and clean waste water. (C) 2008 Elsevier Ltd. All rights reserved.