This paper presents a robust stochastic search algorithm called particle swarm optimization (PSO) to resolve the optimum switching angles for 7-level cascaded multilevel inverter (MLI) to eliminate selected harmonics in order to get low total harmonic distortion (THD) by taking the resultant equations of the output voltage THD of an inverter as an objective function. The simulation is carried out on a 7-level cascaded inverter to ensure the accuracy of the projected technique. Results show that 5th and 7th harmonics are effectively suppressed at faster converging rate and show how the THD varies with modulation index. © Springer India 2015.