The nodes in mobile ad hoc networks are prone to several attacks. This is because these networks are decentralized and any node can join in the network and any node can leave the network. So if any attacker wants to steal some information from the network, the malicious node can be deployed very easily in the network. One of the many possible attacks is the black hole attack. The black hole node shows the source node that it has shortest route to destination even if it does not have any. Therefore, the source node forwards the packets to the path, which are dropped and never reaches the destination node. The proposed scheme detects black hole attack based on the maximum sequence number for each path, which should be received. If in any route reply message, the sequence number were greater than this, the source node would reject the reply on the path. The existing and the proposed schemes were implemented in network simulator 2.35. The performance of network was analysed on the basis of the packet delivery ratio, throughput and remaining energy. These parameters showed improvement over the existing scheme.