The binary complexes of water with styrene and fluorostyrene were investigated using LIF and FDIR spectroscopic techniques. The difference in the shifts of S1 ← S0 electronic transitions clearly points out the disparity in the intermolecular structures of these two binary complexes. The FDIR spectra in the O-H stretching region indicate that water is a hydrogen bond donor in both complexes. The formation of a single O-H⋯π hydrogen-bonded complex with styrene and an in-plane complex with fluorostyrene was inferred based on the analysis of the FDIR spectra in combination with ab initio calculations. The in-plane complex with fluorostyrene is characterized by the presence of O-H⋯F and C-H⋯O hydrogen bonds, leading to formation of a stable six-membered ring. The synergistic effect of O-H⋯F and C-H⋯O hydrogen bonds overwhelms the O-H⋯π interaction in fluorostyrene-water complexes. © 2008 American Chemical Society.