The reaction of 3,6-di(pyridin-4-yl)-1,2,4,5-tetrazine (4-PTA) with trimesic acid (TMA) in methanol solution in a 1.5:1 mole proportion affords molecular complex 1. The structure was confirmed by single crystal X-ray diffraction study. The compound crystallizes in the triclinic space group P-1 with a = 9.7625(11), b = 11.7298(13), c = 13.0734(13), alpha = 68.849(10)degrees, beta = 72.701(8)degrees, gamma = 83.937(9)degrees and Z = 2. The crystal structure of I shows hydrogen bonding between 4-PTA and TMA, and the presence of an interstitial H2O molecule in the crystal. The zig-zag 1-dimensional framework was constructed by the intermolecular hydrogen bond containing O-(HN)-N-..., O-(HO)-O-... and C-(HO)-O-... interactions. The pi-pi interactions are the non-covalent forces operating between the pyridine ring in 4-PTA and benzene ring in TMA to generate 3-dimensional network.