Bidentate Schiff base, 4-[(p-dimethylaminobenzylidene)amino]-3-mercapto-6-methyl-1,2,4-triazin-5-one, and its Co(II), Ni(II), Cu(II) and Zn(II) complexes have been prepared and characterized with the aid of various physicochemical techniques like IR, NMR, ESR, elemental, electronic and thermal analysis. The conductance data suggested the non-electrolytic behaviour of the metal complexes. Fluorescence emission study demonstrated that the metal complexes possess more fluorescent intensity as compared to the Schiff base. Stability of the metal complexes has been checked by using Horowitz-Metzger method. The redox property of Cu(II) complexes has been investigated by using cyclic voltammetry. All the newly synthesized compounds have been screened for their in vitro antimicrobial activity against six microbial strains and it has been found that some of the tested compounds show good antimicrobial activity as compared to standard drug.