AbstractDiaminoguanidine is a useful intermediate for the production of diheterocyclic systems, e.g. of the 5‐aryl‐ or 5‐alkyl‐2‐tetrazoyl‐tetrazole, or the dipyrazoyl‐formimine, types. Investigation of existing methods of the preparation of this substituted hydrazine has revealed some hitherto unobserved facts; e.g. (i) preliminary reduction of nitroaminoguanidine to the diaminoguanidine salt, followed byin situdehydration and cyclization, provides a new route to the alkylaminoiminotriazoles; (ii) hydrazinolysis of the diaminoguanidine hydrazones has been found to take place readily; (iii) although cyanogen chloride and bromide form diaminoguanidine salts with hydrazine hydrate, cyanogen iodide forms an unstable hydrazine complex, without the formation of dia