Abstract Cyclic aminals (N,N-acetals) could be prepared by the reaction of N,N′,N″-triaminoguanidinium sulfate, N,N′,N″-tris(benzylamino)guanidinium chloride or N,N′,N″-tris(benzylamino)guanidine with formaldehyde or acetone. In all cases, 1,2,4,5-tetrazinane derivatives were obtained, which were structurally confirmed by X-ray crystal structure determinations. In two cases, 1:1 cocrystals of two different tetrazinane products were isolated. On the other hand, the reaction of N,N′,N″-tris(benzylamino)guanidinium chloride with benzaldehyde yielded a 3-(2-benzylidenehydrazin-1-yl)-1H-1,2,4-triazole.