Design and development of security-aware and performance efficient routing protocols for Mobile Ad hoc Network is an active area of research. AODV is one of prominent routing protocol for MANET routing. To exchange session key using public key crypto in a single step with route establishment phase CAODV was proposed. Inspired from CAODV in this work we propose a security extension of AODV and developed a new routing protocol for MANET- SCAODV- adding security field which enable the protocol to run in sixteen different modes according to the security desired. The proposed protocol can also exchange session key in single step with route establishment. We evaluate and compare the performance of SCAODV protocol with AODV and CAODV. Simulation results demonstrate that SCAODV consistently outperforms CAODV protocol in terms of routing latency, data packet delay, packet delivery ratio and packet drop. Proposed protocol has the properties of resistance to Spoofed Routing and Secure Key Exchange with Confidentiality, Integrity, Authenticity, Non repudiation and Verifiability.