Nitrite esters of alkanols and cycloalkanols are prepared by treating the alcohol with a solution of nitrosylsulphuric acid in aqueous sulphuric acid and separating the resulting ester from the mixture containing sulphuric acid, ester, alcohol and water. The resulting sulphuric acid solution may be freed from alcohol, concentrated and reacted with nitrous gases to yield fresh nitrosylsulphuric solution. Specified esters are methyl-, ethyl-, butyl-, amyl- and cyclohexyl-nitrates. The process is illustrated by reference to diagrammatic flow sheets (not shown).