Carboxamide complexes having general formula as [ML]Cl-2 center dot nH(2)O (where M = Cu(II), Zn(II); n = 0, 1/2) were synthesized using heterocyclic carboxamide ligands: 1,4-bis[3-(2-thiophenecarboxamido)propyl]piperazine (L-1) and 1,4-bis[3-(2-furancarboxamido) propyl]piperazine (L-2). Their structures were characterized with elemental analysis, molar conductivity, magnetic susceptibility, and spectral methods (H-1-NMR, C-13-NMR, FT-IR, LC-MS). TGA and DTA curves were also performed. The structure-activity relationship for the ligands was investigated using PM3 semi-empirical method. The antibacterial activities of the carboxamides and their complexes were investigated against bacteria; Staphylococcus aureus ATCC 25923, Escherichia coli ATCC 11230, Bacillus magaterium RSKK 5117, B. cereus RSKK 863, Salmonella enteritidis ATCC 13076, B. subtilis RSKK 244 using microdilution method.