Alkylene dithiophosphate derivatives of macrocyclic complexes of nickel (II), having N 2 S 2 potential donors, of the general formula, [(Ni(mc 1 –mc 5 ) ], where mc = macrocyclic ligands and have been synthesized from the reactions of [Ni (mc 1 –mc 5 ) X 2 ], Where X = Cl−, NO 3 −, or CH 3 COO−, with ammonium alkylene dithiophosphates in 1:2 molar ratios in THF. These complexes have been characterized by elemental analysis, molar conductance, molecular weight determination, IR, 31 P NMR, electronic spectra, and magnetic measurements. Molecular weight determination of these complexes indicates their monomeric nature. Octahedral structure has been proposed on the basis of 31 P NMR, electronic spectra, and magnetic measurements. Two sulphur atoms and two nitrogen atoms of the macrocyclic ring coordinate to the central nickel ion in the square planar form, and each dithiophosphate moiety occupies the axial positions binding the central nickel ion in unidentate behavior. Antimicrobial activities of these derivatives have been studied by screening them against fungi, such as Aspergillus flavus, Fusarium oxysporum, Trichoderma harzianum, and bacteria, such as Salmonella typhi and Bacillus subtili. Alkylene dithiophosphate derivatives were found to be more fungitoxic and antibacterial than their corresponding macrocyclic complexes.