Cubic (space group Ia 3, a-10.49 angstrom) bixbyite two-dimensional thulium(III) oxide nanosquare structure was first prepared, and then fully characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction crystallography (XRD), thermogravimetric analysis/differential scanning calorimetry (TGA/DSC), UV-vis-near IR absorption, Raman, X-ray photoelectron spectroscopy, temperature-programmed reduction and oxidation experiments. The crystal structure was fully refined, and detailed structural parameters were determined on the basis of the Rietveld analysis. High resolution TEM image revealed interplanar distances of 0.26 nm and 0.31 nm corresponding to the (4 0 0) and (2 2 2) planes, respectively. The structure projections of the (4 0 0) and (2 2 2) planes were imaged along [0 1 1] and [1 1 -2] directions, respectively. A broad H-2 reduction peak and a sharp 02 oxidation peak were found at 688 C and 123 degrees C, respectively. CO oxidation activity started to appear at 400-500 degrees C. The new results of this study further highlight the characteristics and the actual applications of Tm(III) oxide. (c) 2014 Elsevier B.V. All rights reserved.