Proton-transfer compounds of 2-amino-1-ethanol with halogenated (Hal = Cl (1), Br (2), I (3)) benzoic acids have been prepared and physicochemical characterized by infrared and ultraviolet spectroscopy and singlecrystal X-ray diffraction method. These compounds crystallized in the orthorhombic non-centrosymmetric space group Pna21. The salts units of 1–3 serve as building blocks of the supramolecular architecture and in crystal they are self-assembled via ionic N-H …O and O-H …O hydrogen bonds and generate the molecular synthons R2 2(9). The identical space groups, close similarity of chemical structures and lattice parameters of 1-3 suggest some degree of isostructurality between them. The values of unit cell similarity indexes of P1,2, P1,3, P2,3 are equal to 0.003, 0.02, 0.017 respectively. The structures of 1-3 are obviously isostructural, which is evident by high value of the maximum of volumetric isostructurality indexes [1], which are close to 100% and equal to 99.8%, 97.4%, 97.6% for isostructural pairs 1-2, 1-3 and 2-3 respectively. As expected from the space group (Pna21), 1- 3 may exhibit the second-harmonic generation. For studed compounds the calculations of macroscopic polarisations (P) using the SIESTA [2] method show a sizeable value of P mainly directed along the c axis direction (15704, 13704, 17178 D per unit cell).