Single crystals of a layer-structured coordination polymer, BNAS-11 [ZnTCPP(H2O)Zn-2(H2O)(2)] (ZnTCPP: 5,10,15,20-tetrakis(4-carboxyphenyl)porphyrinatozinc(II)), were obtained. Tetratopic ZnTCPP molecules are connected through dimer zinc paddle-wheel secondary building units and form a two-dimensional (2D) network with square grids. The layers are stacked electrostatically without the need of binding pillar ligands.