A series of M-hmt complexes, where M=Mn2+, Co 2+ were synthesized and studied by single crystal X-ray diffraction. The cobalt complex crystallizes in the triclinic space group P-1 with a=9.098(2)Å, b=9.390(2)Å, c=9.649(2)Å, α=88.3(1)°, β=75.6(2)°, γ=61.64(3)° with Z=1. The Mn complex crystallized in the monoclinic space group P2 1 /n with a=9.511(3)Å, b=16.232(4)Å, c=19.426(5)Å, β=90.6(4)° with Z=4. The structure consists of hexa-coordinated metal cations with water as the ligand having slightly distorted octahedral geometry. The organic ligand, hexamethylenetetramine is not directly coordinated to the metal ion but its presence stabilizes the molecular assembly because of the presence of a rich variety of intermolecular interactions.