The H2O and MeOH complexes of 2-(2′-pyridyl)benzimidazole (2PBI) were investigated using laser induced fluorescence and IR-UV double resonance spectroscopic techniques. The 000 band for the S1 ← S0 electronic transition of 2PBI was observed at 31?616 cm-1, and corresponding transitions for the H2O and MeOH complexes show substantial red shifts of 1059 and 1203 cm-1, respectively. A long progression up to v′ = 5 in the 92 cm-1 vibrational mode was observed for bare 2PBI, which is considerably shortened to v′ = 2 and v′ = 1 for the H2O and MeOH complexes, respectively. The combined experimental and theoretical results suggest that both H2O and MeOH form cyclic complex with 2PBI incorporating N-H⋯O and O-H⋯ N hydrogen bonds. Comparison with other known hydrogen-bonded H2O complexes of bifunctional aza-heteroaromatic molecules suggest that 2PBI-H2O is probably one of the strongest of all known complexes. Further, the experimental data in combination with calculations suggests that the hydrogen atom/proton transfer leading to tautomeric form might be thermodynamically spontaneous in the electronic excited state, due to explicit solvent (H2O and MeOH) participation. © 2010 American Chemical Society.