Heat transfer and turbulent flow characteristics between the ribbed plates have been numerically studied in the present paper. The ribs with the rectangular cross-section have been placed on the top and the bottom plates of the duct, symmetrically. It is assumed that the fluid at 300 K has entered the system while the walls kept at 400 K. All numerical analyses have been performed by k-ω Shear Stress Transport (SST) turbulence model for Re = 10000, 15000 and 20000. For the fixed rib width, the dimensionless height and the dimensionless spacing have been respectively varied as 0.1 ≤ h′ ≤ 0.3 and 0.5 ≤ S′ ≤ 1, and the results have been compared with the ones of the smooth plate. Even though there are twenty-seven cases obtained as a result of parametric combinations, the number of various cases has been reduced from twenty-seven to only nine different variations by applying the Taguchi method. Furthermore, the effects of all the considered parameters on the heat transfer and flow characteristics have been determined in terms of the influence degree. The optimum parameters for Nusselt number and pressure loss have been ascertained individually. What is more, the almost exact values for Nusselt number and pressure loss have also been attained by the confirmation test having an error percentage of 6%. The most dominant factor has been determined as the rib height due to its effect on both heat transfer and flow characteristics. Similarly, with respect to the numerical results, increasing the rib height, the rib spacing and Reynolds number has separately increased Nusselt number. Nevertheless, symmetrical flow structure has been disturbed as a result of ascending the rib height as clearly seen for h′ = 0.3 from the charts. In the meantime, pressure loss has been augmented owing to the increment of the geometrical parameters and also Reynolds number. h′ = 0.1 with S′ = 0.5 at Re = 10000, h′ = 0.2 with S′ = 0.5 at Re = 15000 and h′ = 0.1 with S′ = 0.75 at Re = 15000 can be suggested for the heat transfer enhancement since the pressure loss of the system is tolerated.