In this study, the effects of the rectangular baffles mounted on the bottom surface of a heat exchanger on the heat and pressure drop characteristics were investigated using the Taguchi experimental-design method. Nusselt number and friction factor were considered as performance parameters. An L₁₈(2¹ *3⁵) orthogonal array was selected as an experimental plan for the six parameters: corner angle (α), inclination angle (β), baffle height (H), baffle length (L), baffle width (S) and Reynolds number. First of all, each goal was optimized, separately. Then, all the goals were optimized together, considering the priority of the goals. The presence of the rectangular cross sectioned baffles caused higher pressure drop than that of the smooth channel. It was concluded that increasing inclination angle and corner angle caused heat transfer to decrease. The length of the baffle was found to be the most influential parameter on friction factor. Likewise, it was concluded that the most affected parameter on the heat transfer was Reynolds number.