Wireless Sensor Networks (W) have drawn considerable attention in recent years due to their potential applications. These applications include monitoring active volcano eruption, monitoring the stability of dams, bridges and roads, monitoring sensitive areas of military battlefield, and planetary exploration projects such as lunar exploration for water/ice. W are Ad hoc wireless networks which consist of a large number of densely deployed miniature disposable sensor nodes in the region of interest to monitor and capture physical environmental conditions such as pressure, temperature, humidity, etc. In such a network, environmental data is transmitted in multi hop manner to the base station/sink node for further processing through a wireless link. As the sensors’ placement can be random, such nodes can be placed in dangerous or inaccessible places. Since the sensors are battery powered devices, energy efficiency is considered as one of the main factors in designing routing protocols in W. Power failure of a node affects the node itself and also its ability to forward packets on behalf of others as well as the overall network lifetime. The lifetime of a sensor network can be increased significantly if the operating system, MAC layer and the network layer protocols and even higher layers are designed to be energy aware. From the energy point of view, routing protocols in W are very challenging due to their significant effect on the energy consumptions of nodes. This is because a routing protocol is responsible to deliver data packets in an infrastructure-less network with a large number of nodes which might have mobility. The routing protocols can be divided into five categories including multipath-based, query-based, negotiation-based, QoS-based, and coherent-based. In recent years, various energy efficient routing protocols have been proposed to increase the networks' lifetime. Methods for increasing lifetime of sensor networks through the routing protocols are divided into two categories. In the first category, the routing protocols try to reduce the overall energy consumption. However, in the second category, such protocols try to distribute energy consumption in the entire network. It should be noted that most of the energy-aware routing protocols attempt to decrease the energy consumption of the entire network. Nevertheless, the balance of the energy consumption in the network is more important, which can prevent the network from partitioning. In this way, the query based protocols are efficient from energy consumption perspective. The present thesis proposes an energy efficient query-based routing protocol called EEQR. EEQR is able to reduce the overall energy consumption as well as to balance the energy consumption throughout the network. In addition, EEQR is intended for contexts in which geographic routing criteria are not applicable. Since the positioning systems consume energy, this feature helps to save more energy. The proposed protocol is evaluated using simulation. The simulation results of EEQR are compared with some well-known query-based routing protocols. Simulation results show that the proposed protocol improves network lifetime compared to other query-based routing algorithms in sensor networks. Furthermore, EEQR increases network lifetime by decreasing the packet size and by balancing the energy consumption between network nodes. Keywords: Sensor network, Routing, Energy Aware, GlomoSim, Query-based