The solids Cu(MADH)(2)center dot Cl-2 center dot 2TAT center dot 9H(2)O and Zn(MADH)(2)center dot Cl-2 center dot 2TAT center dot 2H(2)O (MADH = malonic acid dihydrazide and TAT = melamine) characterized by spectroscopic and elemental analysis, have been investigated by transmission electron microscope. Microstructure at high magnification revealed the supramolecular assembly of MADH and TAT into a mesh structure in presence of Cu(II) metal ions and tubular structure with intermittent openings on the tube walls and Y- junctions for Zn(II) complex. The mesh structure of the Cu(II) complex has uniformly spaced 40-50 nm long and 20-30 nm wide openings, while the diameter of the tubular structure of the Zn(II) complex is 50-200 nm. The assembly of the supramolecular structure is attributed to H-bonding and the different architectures of the assembly with different metal ions to the difference in waters of crystallization. The potential of the complex for gas adsorption was also investigated.