Abstract. In this paper, we study energy consumption of mobile twotier wireless ad hoc and sensor networks in comparison with flat mobile wireless ad hoc and sensor networks. Based on idealized wireless network model, we study the total energy expenditure of both these architectures. We provide general formulas for the trajectory of the movement of the mobile nodes in two-tier mobile wireless ad hoc and sensor networks. Finally, we investigate the case with multiple mobile nodes both with their cooperation and without. Simulation results are presented for commonly used network architectures.