The present study describes a new approach for the investigation of electrocatalytic oxidation of hydrazine by using a glassy carbon electrode (GCE) modified by graphene chitosan nanocomposite (Gr-Cs) and Rutin (Ru). The heterogeneous electron transfer rate constant (ks) and the surface coverage of immobilized Ru on the Gr‒Cs/GCE were obtained as 63 s−1 and 4.48×10−11 mole cm−2, respectively. The designed sensor showed excellent electrocatalytic activity toward oxidation of hydrazine. The catalytic rate constant (kcat) of the modified electrode toward N2H4 is 6.3 ×103 M-1s-1. Linear relationship between amperometric current response and hydrazine concentration was observed in the range of 0.3-1500 µM and the limit of detection was 90 nM (S/N=3). In addition, the modified electrode has an excellent anti-interference property in the presence of other potentially interfering species as well as a good operational stability. To evaluate the applicability of the proposed sensor, it was employed to determine hydrazine in a drinking water sample