Crystal structure of the 1:1 complex of pyridine betaine (PyB) with p-hydroxybenzoic acid (HBA) has been determined by X-ray diffraction. The crystals are monoclinic, space group P2 1 /c with the unit cell parameters a=11.9009(4), b=10.3283(3), c=11.0616(4)Å and β=104.252(4)°, Z=4, R=0.038. Both oxygen atoms of the carboxylate group of PyB are linked with the carboxylic and hydroxyl groups of HBA of the neighboring molecules, through two O–H⋯O hydrogen bonds of 2.589(1) and 2.588(2)Å, respectively. The PyB and HBA molecules are connected into infinite chains parallel to the x-axis. The FTIR spectrum of the solid complex is consistent with the X-ray results. 1 H and 13 C chemical shifts of the title complex in D 2 O and DMSO-d 6 and the GIAO/B3LYP/6-31G(d,p) calculated magnetic isotropic shielding tensors (σ) using the screening solvation model (COSMO), δ exp =a+bσ, are reported. In the theoretically optimized structures of the complex investigated the O⋯O distances between PyB and HBA are not the same.