Along with the rigid three-dimensional (3D) coordination networks, the rational design of flexible porous coordination polymers [1] is currently in focus of crystal engineers. The aliphatic dicarboxylic acids with different chain lengths and transition metals with the variable coordination polyhedra are the useful building units for this purpose [2]. Coordination bonds act in the basic framework, while conformational flexibility of the ligands’ aliphatic skeleton and hydrogen bonds direct a flexible dynamic structure [3]. Herein, we report the mixed-ligand one-dimensional (1D) coordination polymer with the composition [Cd2(suc)(Hsuc)2(nia)4]n I, where H2suc=succinic acid and nia=nicotinamide, and with the {Cd2(COO)4} binuclear cluster as the secondary building unit (SBU). Compound I crystallizes in the monoclinic space group P21/n: a=11.4313(3), b=14.6649(3), c=12.9413(4) Å, β=102.751(3) °. In the centrosymmetric SBU each Cd(II) atom is heptacoordinated in the N2O5 coordination environment. The succinate anions exist in two different deprotonated states, Hsuc– and suc2–. The Hsuc– anion, as a terminal ligand, bridges two Cd atoms in a syn-syn mode, the Cd···Cd separation being of 3.912 Å. Contrary, the suc2– anion acts as a bridge with bis-chelating mode, giving rise to the 1D coordination chain (Fig.) with the Cd···Cd separation across it of 9.124 Å. The axial positions occupy nitrogen atoms from two terminal nia ligands.figureTwo types of homomeric supramolecular synthons, the amide, NH…O(O=C), R22(8) and carboxylic COOH…COOH, R22(8) ones, provide the aggregation of coordination chains into 3D network. The two-fold interpenetration is achieved via amine-carboxylate heterosynthon. The pyridine rings of nia ligands in the 1D chain are separated by the distance of 4.099 Å reachable for weak π–π stacking interactions.