The crystal structures ofN′-aminopyridine-2-carboximidamide (C₆H₈N₄),1, andN′-{[1-(pyridin-2-yl)ethylidene]amino}pyridine-2-carboximidamide (C₁₃H₁₃N₅),2, are described. The non-H atoms in compound1are nearly planar (r.m.s. deviation from planarity = 0.0108 Å), while2is twisted about the central N—N bond by 17.8 (2)°. Both molecules are linked by intermolecular N—H...N hydrogen-bonding interactions;1forms a two-dimensional hydrogen-bonding network and for2the network is a one-dimensional chain. The bond lengths of these molecules are similar to those in other literature reports of azine and diimine systems.