The stability of Methyltetrazine-Amine is substantially improved compared to hydrogen substituted Tetrazine-amine. Superior stability of Methyltetrazine-Amine allows this reagent to be used in wider range of chemical transformations. Long-term storage of Methyltetrazine-Amine, especially in aqueous buffer, is also greatly improved compared to Tetrazine-Amine. This reagent is supplied as HCl salt for improved stability and easy handling.