We report a hydrogen peroxide (H2O2) and hydrazine sensor based on novel copper sulfide vertical bar reduced graphene oxide (CuS vertical bar rGO) nanocomposites, which were synthesized with a facile hydrothermal method. It was discovered that the aggregation of graphene nanosheets could be reduced very significantly by the formation of CuS vertical bar rGO composites. The sensor was fabricated by simple casting of CuS vertical bar rGO aqueous suspension on glassy carbon electrode (GCE) and its performance was evaluated by cyclic voltammetry and amperometric techniques. It was found that the resulting sensor exhibited good performance toward H2O2 detection with wide linear response ranging from 1 x 10(-6) to 1 x 10(-3) M (R = 0.996) at -0.2 V and low detection limit of 1 x 10(-7) M estimated at a signal-to-noise ratio of 3. In addition, the fabricated sensor also exhibited high sensitivity toward the detection of hydrazine with a low detection limit of 3 x 10(-7) M, wide linear range from 1 x 10(-6) to 1 x 10(-3) M (R = 0.999) at 0.4 V. For both analytes, the sensor exhibited good reproducibility, selectivity and stability. (C) 2014 Elsevier Ltd. All rights reserved.