An investigation of supramolecular synthons of p-hydroxybenzoic acid (PHBA) has been carried out in this work. Three different kinds of compounds derived from PHBA (hydrate (1), co-crystal (2) and salt (3)) have been synthesized and characterized by single-crystal X-ray diffraction, infrared spectroscopy, differential scanning calorimetry (DSC) and thermogravimetric analyses (TGA). A thorough structural investigation revealed the different supramolecular synthons patterns of the three compounds: hydrate (1) displays 1-D supramolecular sheet completed by water molecules; co-crystal (2) displays square grid structure completed by hetero-dimeric unit; and salt (3) forms hetero-dimeric unit and displays infinite zigzag striped structure. We further prepared Hirshfeld surfaces for compounds 1-3 as well as PHBA, accompanied by vibrational spectroscopy, for the in-depth studies of intermolecular interactions in their solid-state forms. (C) 2013 Elsevier By. All rights reserved.