The products obtained after ignition in furnace were leached in 1 M HCl solution for 15 h in order to remove MgO and minor phases and to obtain pure ZrB2. Fig. 2(b) shows the XRD pattern of the leached product. MgO was completely eliminated after the leaching process, however; other minor phases could not be removed. After leaching, the final product contained ZrB2, ZrO2, Zr2ON2 and Mg3B2O6.