Methods of preparing boron suboxide are provided herein. In some embodiments, a method for preparing boron suboxide may include loading elemental boron powder into a furnace; purging the furnace by flowing a first gas comprising one of nitrogen or an inert gas into the furnace; heating the boron powder in a reactive atmosphere comprising a mixture of argon and a non-reducing oxygen-containing gas to convert elemental boron powder into boron suboxide powder, wherein the amount of oxygen in the reactive atmosphere is no greater than about 1%.