<p>To optimize the performance of a pentagonal ribs-equipped cooling passage, that is, maximization of heat transfer with minimization of pumping power, the Taguchi method was employed to identify the best suitable combination of flow and design parameters. Based on the L₁₆ (4³) orthogonal array design, heat transfer experiments with liquid crystal thermography were performed to assess the influence of main control parameters: Reynolds number (Re; A: 9400–58850), relative rib spacing (p/e; B: 6–12), and pentagonal angle (<i>α</i>; C: 0°–15°). The pentagonal rib design substantially reduces friction factor (<i>f</i>) while enhancing Nusselt number (Nu), which contributes to superior performance compared with square ribs. The optimal combinations of flow and design parameters for Nusselt number, <i>f</i>, and thermohydraulic performance are A₄B₂C₂, A₂B₄C₃, and A₁B₃C₂, respectively. Re has the greatest influence on thermohydraulic performance with a contribution of 66.17 % followed by <i>α</i> and rib spacing with contributions of 21.51 % and 12.32 %, respectively.</p>