The structure of a liquid crystal with intramolecular hydrogen bonding, 5-butoxy-2[(4-butylphenyl)azo]phenol, was determined by using X-ray diffraction of a single-crystal and NMR studies in the nematic phase. Because the uncertainties in the positions of the hydrogen atoms are quite large in the X-ray structure, some of the bond distances and bond angles of the mesogenic core were determined by the use of C-13 NMR. For the liquid crystals in natural abundance, H-1-C-13 dipolar coupling constants were obtained from the 2D technique of proton-encoded local field spectroscopy. For an analogue with deuterium substitution in the hydrogen-bonded position, H-2-C-13 dipolar coupling constants were obtained from 1D 13C-{H-1} spectra. The dipolar coupling constants were used to calculate the order parameters of the phenyl rings, as well as the bond distances and bond angles in the hydrogen-bonded moiety.