The nitrosonium ion is NO⁺, in which the nitrogen atom is bonded to an oxygen atom with a bond order of 3, and the overall diatomic species bears a positive charge. This ion is usually obtained as the following salts: NOClO₄, NOSO₄H (nitrosylsulfuric acid, more descriptively written ONSO₃OH), and NOBF₄. The and salts are slightly soluble in CH₃CN. NOBF₄ can be purified by sublimation at 200–250 °C and .