Initial oxidation of a ZrB2(0 0 0 1) surface at high temperature yields a new 2 x 2 ordered surface structure, as characterized using reflection high-energy electron diffraction (RHEED), Auger electron spectroscopy (AES), high-resolution electron energy loss spectroscopy (HREELS), and X-ray photoelectron spectroscopy (XPS). During high-temperature treatment in O-2, the surface becomes boron-deficient. In the surface oxide layer, Zr is not fully oxidized, but in a Zr3+ state. The HREELS shows strong loss peaks, showing insulating characteristics of the surface. (C) 2009 Elsevier B.V. All rights reserved.