A cobaltion-5-（5-iodide-2-pyridylazo）-2,4-diamino toluene（5-I-PADAT）（Co2+-5-I-PADAT） modified electrode was prepared via cyclic voltammetric electrodeposition with Co2+-5-I-PADAT,a coordination compound as supporting electrolyte in the scanning potential range of-1.5-0.5 V by 50 deposition circles.The morphology and composition of the modified electrode were characterized by scanning electron microscopy and X ray crystalline diffraction.The electrocatalytic oxidation behavior of hydrazine on the modified electrode was also investigated.Results indicated that a significant hydrazine oxidation peak appeared at a potential of 0.55 V in a pH 7.0 phosphate buffer solution.Based on that,a novel method for the quantitative analysis of hydrazine was established.There was linear relationship for the oxidation peak current with hydrazine in the concentration range of 0.64-2 150 μmol/L with a correlation coefficient of 0.998 0.The detection limit（S/N=3） was 0.28 μmol/L,and the recoveries were in the range of 95.3%-102%.With the advantages of good reproducibility and selectivity,the sensor could satisfy the requirements for detection of hydrazine in environmental samples.