Rigid meta-phosphonobenzoic acid 2 possesses two functional groups (phosphonic acid and carboxylic acid) both having the aptitude to associate with a metallic precursor to form hybrid materials. The hydrothermal reactions of compound 2 with MnCl2·4H2O or Co(NO3)2·6H2O produce, respectively, the isostructural layered materials M(H2O)(PO3C6H4CO2H) (3, M = Mn; 4, M = Co) characterized by the presence of the free carboxylic acid groups in the interlayer space (space group P21/n). The reaction of Zn(CH3COO)2·2H2O with 2 produces two different materials depending on the pH of the reaction media. At low pH (pH < 4.1), the isostructural material Zn(H2O)(PO3C6H4CO2H) (5) is formed possessing ZnII atoms octahedrally coordinated. At higher pH, generated by the addition of urea in the hydrothermal reaction, Zn3(H2O)2)(PO3C6H4CO2)2 (6) is formed (orthorhombic; space group Pcan). In material 6, the phosphonic acid and the carboxylic acid groups are linked to the inorganic network. One of the two ZnII centres is tetrahedrally coordinated and the other is surrounded by a trigonal bipyramid