Nitrosylsulfuric acid

Nitrosylsulfuric acid is the chemical compound with the formula NOHSO4.

This salt is a source of the NO+ ion, It can also be viewed as the mixed acid anhydride of sulfuric acid and nitrous acid:
 * HNO2 +  H2SO4  &rarr;  NOHSO4  +H2O

NOHSO4 is useful in organic chemistry to prepare diazonium salts from amines. A typical procedure entails dissolving sodium nitrite in concentrated sulfuric acid in an ice bath.

Related NO-delivery reagents include nitrosyl fluoroborate, [NO]BF4, and nitrosyl chloride.