Crystal structures of three derivatives of phenylpropionic acid, 2, 3 and 4 with hydroxyl, methyl and methoxy substitutions at the 2, 4 positions have been determined from X-ray powder diffraction data and their electronic structures were calculated at the DFT level. The optimized molecular geometries agree closely to that obtained from the crystallographic analysis. Intermolecular O-H center dot center dot center dot O hydrogen bonds generate R-2(2)(8) rings, which are further connected through O-H center dot center dot center dot O and C-H center dot center dot center dot O hydrogen bonds into two-dimensional framework in 2 and 4, and a step like architecture in 3. The HOMO-LUMO energy gap (> 4.0 eV) indicates a high kinetic stability of the three compounds. (C) 2010 Elsevier B. V. All rights reserved.