In crystalline state 2,5-dichloro-3,6-dihydroxy-p-benzoquinone (chloranilic acid, CLA) forms with 4,4′-di-t-butyl-2,2′-bipyridyl (dtBBP) the hydrogen bonded chains along the b-axis. From one side of the CLA molecule the proton transfer takes place and the hydrogen bond length is very short (2.615Å). A continuous infrared absorption is observed for dtBBP·CLA in the wavenumber range between 3100 and 800cm −1 also indicating the strong hydrogen bonds. The DSC measurements show a weak, close to continuous, phase transition at 414K. The complex dielectric permittivity for a single crystal sample was measured in the temperature range 100–440K and at frequencies between 200Hz and 2MHz. The dielectric response is a combination of semiconducting properties and a relaxation process most probably connected with the proton dynamics in the hydrogen bonds. The mechanism of the structural phase transition is discussed.