Particle Swarm Optimization based secure QoS clustering for Mobile Ad hoc Network Abstract Mobile ad hoc network is a dynamic wireless network of mobile nodes without any centralized control. Energy efficient routing is the most challenging task of MANET. Clustering in MANET gives energy efficient solution. In this paper we proposed a secure clustering algorithm using multi-objective particle swarm optimization technique. The algorithm uses three objective functions based on nodes QoS parameters: trust value, life time and available bandwidth. The main advantage of MOPSO is that it provides multiple solutions at a time through optimal Pareto front. The proposed approach is simulated with MATLAB and NS2. Here we have discussed the performance of the proposed approach by varying number of nodes and transmission range of nodes.