This investigation reports the combined effect of synthetic jet and a surface-mounted rib on heat transfer in a square cross-section channel flow. The rib height to hydraulic diameter ratio is equal to 0.1625. The Reynolds number of the channel has been set equal to 5500. The synthetic jet actuator has been operated at different actuation voltages with different amplitude modulation frequencies. At actuation voltage of 55 V, the maximum overall heat transfer is enhanced by 132.6% compared with smooth duct flow.