This research is aimed to evaluate the performance of two prominent on-demand Reactive routing protocols AODV & DSR in order to achieve optimal performance in Mobile Ad hoc Network. My research efforts are focused on simulation experiments to explore several parameters such as traffic patterns, node density and initial pattern of nodes that may affect the routing performance. After the extensive simulation study, I will try to suggest various possible combinations of MANET routing protocols for various MANET scenarios, in order to get optimal performance. The major contribution of this research work includes the characterization study of different routing protocols using a different routing mechanism to MANET based on the observations, Finally, The attempt is made to recommend how the performance of AODV can be improved by varying the mobility speed in the scenario where network load exceeds a level. The evaluation in this research is performed by means of simulation using Network simulator 2.33 from Berkeley.