A novel, highly active three-way catalyst, rhodium supported on Y-and La-added zirconia (Rh/Zr-Y-La-O), was found in this study. Rh/Zr-Y-La-O showed superior performance to a previously reported Rh on La-added ZrO 2 (Rh/Zr-La-O) catalyst (Kawabata et al., Chem. Commun., 2013, 49IJ38), 4015; Catal. Sci. Technol. 2014, 4(3), 697). 21,22 The effects of Y addition to ZrO 2 -based supports were investigated in detail.CO temperature-programmed reduction and in situ Fourier transform infrared spectra of adsorbed NO species indicated that Y addition to La-containing ZrO 2 enhanced the reducibility of rhodium supported on the catalyst and that more metallic Rh was exposed on the surface after the oxidation of Rh/Zr-Y-La-O than of Rh/Zr-La-O. Before and after an aging treatment at 1273 K that simulated 80 000 km travelled by vehicles, Rh/Zr-Y-La-O showed high steam reforming activity. After the aging treatment, Rh/Zr-Y-La-O was deactivated using an oxidation treatment, but its three-way catalysis activity was completely regenerated after a short (5 min) exposure to steam reforming reaction conditions, demonstrating selfregeneration capability. After the aging treatment, Rh/Zr-Y-La-O showed higher rhodium dispersion than other catalysts. This was attributed to the high surface area of the support after aging and the stabilization of ZrO 2 by the addition of Y. Our findings highlight the role of catalyst supports in designing effective three-way catalysts with high tolerance to the oxidative conditions in new vehicles and engines. 584 | Catal. Sci. Technol., 2015, 5, 584-594 This journal is 82 424 5494; Tel: +81 82 424 7741 † Electronic supplementary information (ESI) available: CO conversion, EDX analysis data, XRD patterns of the Rh 111 diffraction peak and XPS spectra are provided. See