Mobile Ad Hoc Networks (MANET’s), due to their lack of physical infrastructures or centralized online authorities, pose a number of security challenges to a protocol designer. Traditional network authentication solutions rely on trusted third party servers (Certificate Authorities, CA These servers should physically be present in the network However, ad hoc networks are infrastructure-less, and there is no centralized server for key agreement. Hence traditional solutions do not meet the requirements of mobile ad hoc networks. We propose a key agreement protocol for pairwise key establishment in mobile ad hoc networks which does notrequire any centralized support