In this work, we report a novel electrochemical sensor for sensitive determination of Imidacloprid by facile electrodeposition of Ag nanodendrimers (AgNDs) on the graphene nanosheets (GNs) modified glassy carbon electrode (GCE). The AgNDs were directly electrodeposited on the electrode surface via potentiostatic method without using any templates, surfactants or stabilizers. Preparation, characterization and application of this sensor were systematically investigated. The relationship between AgNDs morphological evolution and electrodeposition conditions (applied potentials and times) was investigated. The morphology and constituent of the AgNDs/GNs/GCE surface was characterized using scanning electron microscopy (SEM), energy dispersive X-ray (EDX), X-ray diffraction (XRD) and electrochemical impedance spectroscopy (EIS) techniques. The electrochemical experiments exhibited remarkable catalytic activity of AgNDs/GNs/GCE toward Imidacloprid reduction. The treelike hierarchical structure of nanodendrimers is an appropriate structure for design of effective electrocatalysts. Moreover, the synergistic effect between GNs and AgNDs significantly improves the electrochemical responses. Determination of Imidacloprid by differential pulse voltammetry (DPV) method represented a wide linear range of 1.0 x 10(-6) to 1.0 x 10(-4) M with detection limit of 8.14 x 10(-7) M. The proposed electrode displayed excellent repeatability and long-term stability; furthermore, the practicability of this sensor was successfully demonstrated by determination of Imidadoprid in several real samples. (C) 2017 Elsevier B.V. All rights reserved.