The hydrogen-bonded complex of 4-hexyloxybenzoic acid and 4,4'-bipyridine (HOBA-BPy) was selected as an example to study the dynamic behavior of the hydrogen-bonded mesogens in liquid crystalline state by using temperature-variable FTIR (TV-FTIR). We found that there exist two dynamic equilibria of hydrogen bonding dissociation-association in the melting state of the complex, and the liquid crystallinity of the complex should be contributed from both of the two mesogens, HOBA...BPy...HOBA and (HOBA)(2) dimers.