Mobile ad hoc network (MANET) is a special type of wireless network in which arncollection of wireless mobile devices (called also nodes) dynamically forming a temporaryrnnetwork without the need of any pre-existing network infrastructure or centralizedrnadministration. Currently, Mobile ad hoc networks (MANETs) play a significant role inrnuniversity campus, advertisement, emergency response, disaster recovery, military use in battlernfields, disaster management scenarios, in virtual classrooms, in emergency search and rescuernoperations, data acquisition in hostile environments, communications set up in exhibitions,rnconferences and meetings, in sensor network, extension of cellular networks, at airport terminalsrnfor workers to share files and so on. In MANETs, there is no pre-established infrastructure tornfacilitate the routing activity and hence communication between mobile nodes can be achievedrnthrough the mobile nodes using multi hop wireless technique. However, wireless devices in adrnhoc networks are typically limited power with limited life span. Thus, energy efficiency is arncritical issue for battery-powered mobile devices in ad hoc networks. This is due to the fact thatrnfailure of node or link allows re-routing and establishing a new path from source to destinationrnwhich creates extra energy consumption of nodes and sparse network connectivity, leading to arnmore likelihood occurrences of network partition. Routing based on energy related parameters isrnone of the important solutions to extend the lifetime of the node and reduce energy consumptionrnof the network.rnIn this dissertation, we evaluated energy efficiency of an existing routing protocols ofrnMANETs based on energy efficient metrics and designed a novel energy aware routing protocolsrncalled Balanced Battery Usage routing (BBU in short) and Gossip based Balanced BatteryrnUsage routing (GBBU in short) which uses residual energy, hop count and node density as a costrniirnmetric to minimize energy consumption, maximize network lifetime and distribute usage ofrnenergy among mobile nodes of MANET. The new protocols, which are referred to BBU andrnGBBU, are simulated using Network Simulator-2.35 and comparisons are made to analyze itsrnperformance based on network lifetime, delivery ratio, normalized routing overhead, averagerncollision rate, normalized energy consumption, standard deviation of residual energy of all nodesrnand average end to end delay for different network scenarios. The simulation results reveal thatrnthe proposed energy aware routing protocols make the network active for longer interval of timernonce it is established by minimizing energy and distributing energy consumption across mobilernnodes on the network at the trade off a small amount of end to end delay. For instance, thernsimulation results of BBU showed an average improvement of 9.15% and 6.83% in networkrnlifetime compared to ad hoc On-Demand Distance Vector protocol (AODV) and Alternate LinkrnMaximum Energy Level AODV (ALMEL-AODV) respectively. Furthermore, a 15.77% and 11.4%rnreduction of standard deviation of residual energy of all Nodes is also achieved in BBUrncompared to AODV and ALMEL-AODV. However, BBU increased end to end delay by a 5.75%rncompared to standard AODV but still achieved a 4.85% better performance compared tornALMEL-AODV. A further extension of the approach using gossiping technique (GBBU) leds tornan average improvement in normalized energy consumption by 12.36% and 6.39% under variousrnnetwork density, 13.34% and 9.16% under different traffic loads, 10% and 6.23% under differentrnmobility at the trade off an increase in end to end delay by 6.07% and 2.55% under variousrnnetwork density, 3.94% and 4.19% under different mobility compared to AODV and GOSSIPrnrouting protocols.