Dissertation (MSc Information Technology)Wireless Sensor Networks (WSNs) usually consist of sensor nodes and gateways with limited resources such as memory, power and size. As a result, WSNs require bandwidth-efficient, memory-efficient and energy-efficient application protocols for data transmission. If data transmission at the application layer is not efficient, more re-transmissions will occur across the network which consumes limited resources of the WSN. Therefore a careful and extensive performance evaluation is needed for the application protocols in use by any WSN. Two existing application protocolsin WSN were evaluated namely Hypertext Transfer Protocol (HTTP) and Constrained Application Protocol (CoAP).The performance evaluation was done using Cooja that emulate Contiki operating system and Z1 motes. Performance evaluation was done based on two metrics namely Resource Retrieval Time (RRT) and bytes per transaction. Based on the analysis of the simulation data under different scenarios, the performance of HTTP and CoAP were evaluated and the results showed that CoAP performs better than HTTP. Simulation results revealed that CoAP messages have lower RRT than HTTP. Moreover, CoAP messages generated lower overhead resulting to lower bytes per transaction as compared to HTTP. Results advocate CoAP as a better protocol for WSN. CoAP ensures short sessions with lower overhead which enables lower memory and bandwidth requirements. In addition to that, CoAP conserves energy of motes by having lower transmission overhead.