In strong acidic solution, hydrated 1,3-propanediaminetetraacetato zinc nitrate [Zn(NO 3 ) 2 (H 2 O)(1,3-H 4 pdta)] n (1) and its substituted products [ZnBr 2 (H 2 O)(1,3-H 4 pdta)] n (2), and [Zn(NCS) 2 (H 2 O)(1,3-H 4 pdta)] n (3) (H 4 pdta=1,3-propanediaminetetraacetic acid, C 11 H 18 N 2 O 8 ) were isolated as one-dimensional coordination polymers. The former is an additive of zinc nitrate and H 4 pdta. Substitution of nitrate 1 with bromide or thiocyanate results in the formation of 2 and 3 at pH values between 0.5 and 1.0. In the neutral complexes 1–3, the 1,3-H 4 pdta ligand links consecutive monomeric [ZnX 2 (H 2 O)] (X=NO 3 , Br and NCS) units to generate an infinite 1D chain, which contains strong intra-molecular hydrogen bonds [O1w⋯O2 for 1: 2.707(3)Å; for 2: 2.663(5)Å; for 3: 2.678(4)Å], which are extended into a 3D supramolecular structure by very strong inter-molecular hydrogen bonds [O4⋯O2b for 1: 2.539(3)Å, x, y, z−1; for 2: 2.479(5)Å, x, y, z−1; for 3: 2.568(4)Å, x+1, y, z]. Compound 1 is very soluble in water and can be traced by a solution 13 C{ 1 H} NMR technique, which is compared with the solid state NMR spectra of 1–3.