Abstract :Integration of shunt capacitor are widly used in the distribution system, to supply reactive power and also it is considered one of the effective ways of reducing power system losses, enhancing voltage profile and improve system capacity. The appropriate placement of capacitor is also important to ensure that system power losses and total capacitor cost are minimal. In this paper the proposed methodology uses Particle Swarm Optimization (PSO) algorithm and loss sensitivity index to distinguish the optimal sizing and location respectively of capacitor in radial distribution network to reduce total power losses and their cost and improve the voltage profile. The effectiveness of the proposed method is demonstrated by the application on standard IEEE 85-bus radial standard distribution test system. Keywords : Shunt capacitor, reactive power, Power Loss, Voltage Profile, capacitor cost, Particle Swarm Optimization, loss sensitivity index, IEEE 85-Bus