To enhance the performance of gas turbine, it is necessary to operate at high inlet gas temperature, which required more effective cooling method for turbine blades. The ribs, protrusion and dimples are efficient turbulators for heat transfer augmentation. In the present study new compound structure of multi semicircular rib-dimple are presented experimentally and val-idated with simulation/optimization techniques to achieve pressure drop and heat transfer characteristics. Multi semicircular rib with 10 and 20 dimples are investigated and placed at the bottom surface of a rectangular channel. The experiment was conducted by considering the data such as: Reynolds numbers (Re) 12,000 to 30,000, Rib pitch (P) to height (e) ratio = 8 to 10, rib height (e) to channel hydraulic diameter (Dh) ratio = 0.15 and dimple depth (δ) to dimple diameter (d) ratio = 0.2. It is found that the combination of multi semicircular rib with 20 dimples shows the maximum thermal performance over multi semicircular rib with 10 dimples and rib alone channel. Friction loss found more in compound channel with 20 dimples whereas less in the 10 dimples. Compound channel with 20 dimples enhanced 30 % more heat transfer over 10 dimples and 25 % additional than the rib alone channel, also multi semicircular rib shows the least thermal performance.