The investigations concerning the thermal behaviour of a series of Ni(II) and Cu(II) complexes of type [NiLCl2]·mH2O ((1) L:L1, m=6; (3) L:L2, m=4) or [CuLCl]nCln·mnH2O ((2) L:L1, m=6; (4) L:L2, m=4) are presented. The ligands L(1) and L(2) have been synthesised by template condensation of 3,6-diazaoctane-1,8-diamine
or 1,2-diaminoethane with formaldehyde and 2-amino-4H-1,2,4-triazole. The bonding and stereochemistry of the complexes have
been characterised by IR, electronic and magnetic studies at room temperature. The in vitro qualitative and quantitative antimicrobial
activity assays showed that the complexes exhibited variable antimicrobial activity against planktonic as well as biofilm
embedded Gram-negative, Gram-positive and fungal strains. The thermal behaviour provided confirmation of the complexes composition
as well as the number and nature of water molecules and the intervals of thermal stability.