Methyldiazonium is an organic compound consisting of a methyl group attached to a diazo group.

This cation is the conjugate acid of diazomethane, with an estimated pKa<10.

[1] It is an intermediate in methylation reactions of diazomethane with acidic hydroxyl compounds, such as conversion of carboxylic acids to methyl esters and phenols to methyl ethers.

[2] It has been implicated as the metabolite of N-nitrosodimethylamine responsible for the observed carcinogenicity of that compound.

This organic chemistry article is a stub.