Endwall heat transfer measurements for a radially rotating rectangular pin-fin channel with the width-to-height ratio (aspect ratio) of 8 are performed at the parametric conditions of 5000≤Re≤20000, 0≤Ro≤l.4 and 0.l≤Δρ/ρ≤0.21. Centerline heat transfer levels along the leading and trailing endwalls of the rotating pin-fin channel are respectively raised to 1.77-3.72 and 3.06-5.2 times of the Dittus-Boelter values. No previous attempt has examined the heat transfer performances for the pin-fin channel at such high rotation numbers. A selection of experimental data illustrates the individual and interactive Re, Ro and buoyancy number (Bu) effects on heat transfer. Spanwise heat transfer variations between two adjoining pin rows are detected with the averaged Nusselt numbers (Nu) determined. A set of empirical equations that calculates Nu values over leading and trailing endwalls in the developed flow region is derived to correlate all the heat transfer data generated by this study and permits the evaluation of interactive and individual effects of Re, Ro and Bu on Nu. With the aid of the Nu correlations derived, the operating conditions with the worst heat transfer scenarios for this rotating pin-fin channel are identified.