This paper presents the Bacterial Foraging Optimization (BFO) for elimination of harmonics in a cascaded H-bridge multilevel inverter (MLI). The main aim is to eliminate the dominant lower-order harmonics which is done by solving nonlinear transcendental equations, while maintaining the maximum fundamental component. In this paper, the BFOA algorithm which basically deals with the food foraging behavior of bacteria is applied to a 7-level cascaded MLI for solving these equations. The performance of the BFO is evaluated and the graphs between Switching Angles and Total Harmonic Distortion (THD) with various Modulation Indices (MI) shows that the proposed method gives best optimal solution between MI in the range of 0.7–0. 8. The results show that 5th and 7th harmonics are reduced and are maintained minimum. © Springer India 2015.