In the title complex, C22H36N4O10, cyclic eight-membered hydrogen bonded rings exist involving 2-aminopyridinium and adipate ions. Adipic acid molecules and adipate ions are linked in zigzag chains by O-H...O hydrogen bonds. The characteristic IR absorption bands of 2-aminopyridinium adipate monoadipic acid dihydrate were observed as; 35002500 cm(-1) region (hydrogen bonded O-H and N-H stretch), 1695 cm(-1) (carboxylic C=O stretch), 1595 cm(-1) (C=N ring stretching and N-H bending vibrations), 1565 and 1395 cm(-1) (asymmetrical and symmetrical stretch of carboxylate ion, respectively). The title complex showed two thermal decomposition steps. Crystallization water release in the first step (105-118 degreesC) and remaining anhydrous complex decomposition completely in the second step (120-450 degreesC). (C) 2003 Elsevier Science B.V. All rights reserved.