Mobile Ad Hoc Networks (MANETs) are important because they are widely used in war zones, rescue missions and other civilian applications where it is almost impossible to use any other networks. MANETs are temporary networks where nodes are allowed to join or leave the network at any point in ~ime. Though MANETs offer flexibility, self maintenance and dynamic topology, they suffer from limited resources, have less computational power and are susceptible to attacks. Due to the dynamic nature of MANETs, the secure transmission of data is one of the key issues in MANETs. Thus there is a need to safeguard the network from internal as well as external security threats. In this paper, I attempt to improve the security environment of one of the most popular routing protocols in MANETs, the Ad Hoc On Demand Distance Vector Routing Protocol (AODV). AODV is a reactive protocol which guarantees loop free routes during the transmission of data, and the focus of this paper is mainly to secure the AODV protocol against black hole attacks. This paper proposes the Forward Reaching Black Hole Detection algorithm (FRBD) to detect single black holes in MANETs that are based on the AODV routing protocol. This paper presents a solution that includes slight modifications in the functioning of the AODV protocol. I demonstrate the proposed solution on a specially developed Java based simulation tool. The paper examines the black hole detection capabilities of the FRBD algorithm by applying it on randomly generated problem instances. These instances vary based on the total number of nodes, paths and the location of the black hole node. Our analysis shows that the FRBD algorithm effectively detects single black holes in the network and thus improves the overall security of MANETs.