This study experimentally detected the endwall Nusselt numbers (Nu) distributions, Fanning friction factors (f) and thermal performance factors (TPF) for a stationary S-shaped two-pass square channel with the associated turbulent flow fields analyzed by ANSYS Fluent code to disclose the flow mechanisms responsive to the measured thermal performances. The full-field Nu distributions over the endwalls of present S-shaped inlet/outlet legs and 180 sharp bend at Reynolds numbers (Re) of 5000, 7500, 10,000, 12,500, 15,000, 20,000 and 30,000 Were measured using the steady-state infrared thermography method; while the validated RNG k-epsilon turbulence model was adopted to reveal the fields of time-mean fluid velocity, turbulent kinetic energy and cross-plane secondary flow. Acting by sectional vortices induced along the inlet/outlet S-pathways and 180 degrees sharp bend, the core-to-wall momentum/heat exchanges are boosted to elevate both Nu and f values. Accompanying with the f augmentations from 10.19-8.27 times of Balssius f(infinity) levels, the area-averaged Nusselt numbers ((Nu) over bar (A)) over the entire S-shaped endwall were elevated to 3.21-3.09 times of Dittus-Boelter Nusselt number (Nu(infinity)) values at 5000 <= Res <= 30,000, resulting in the TPF between 1.4 and 1.44. To assist relevant engineering applications, two sets of empirical correlations evaluating the regionally averaged endwall Nusselt numbers and f factors are devised. (C) 2016 Elsevier Ltd. All rights reserved.