Two new crystalline solids, namely, 5-aminotetrazole–3,5-dihydroxybenzoic acid–water (1/4/6), CH3N5·4C7H6O4·6H2O (I), and 5-aminotetrazolium 3,5-dinitrosalicylate, CH4N5 +·C7H3N2O7 − (II), have been synthesized and characterized by single-crystal X-ray diffraction and Hirshfeld surface analysis. The crystal packing arrangements of I and II are governed by N—H...O and O—H...O hydrogen-bonding interactions. In cocrystal I, adjacent acid molecules are linked through O—H...O hydrogen bonds, forming a dimer with an R 2 2(8) motif. In salt II, the tetrazolium cation and acid anion are linked through N—H...O hydrogen bonds to also form a dimer with an R 2 2(8) motif. Further N—H...O and O—H...O hydrogen bonds help to stabilize the crystal packing, along with aromatic π–π stacking interactions in I and carbonyl...π interactions in II. The Hirshfeld surface analysis and fingerprint plots reveal that O...H/H...O interactions contribute 34.4% of the total interactions in the crystal packing of cocrystal I and 36.7% in salt II.