The invention provides a boron suboxide composite material comprising boron suboxide and a secondary phase, wherein the secondary phase contains a boride. The boride may be selected from the borides of transition metals of the fourth to eighth groups of the periodic table. Particularly, the boride may be selected from the borides of iron, cobalt, nickel, titanium, tungsten, hafnium, tantalum, zirconium, rhenium, molybdenum or chromium. The boride also may be a platinum group metal boride, preferably palladium boride. The secondary phase also may contain one or more oxides.