A novel Azo-Schiff base ligand L 2-[1.5-Dimethyl-3-[2-(5-methyl-1H-indol- 3-yl) - ethylimino] - 2 - phenyl - 2,3 - dihydro - 1H - pyrazol - 4 - ylazo] - 5- hydroxy -benzoic acid has been synthesized from reaction 1.5-Dimethyl-3-[2-(5- methyl- 1H - indol - 3 - yl) - ethylimino] - 2 - phenyl - 2.3 - dihydro - 1H - pyrazol - 4 - ylamine (A) with m-hydroxy benzoic acid. Then, its Zn(II), Cd(II) and Hg(II) complexes were synthesized with the general formula [ML1Cl] where M = Zn(II), Cd(II) and Hg(II) are reported. The ligand and its metal complexes have been characterized by elemental analysis, metal content, Chloride containing, molar conductance, FT-IR, 1H and 13C- NMR, UV-Vis spectra, magnetic susceptibility, thermal analysis, and mass spectra. The activation thermodynamic parameters, such as ΔE*, ΔH*, ΔS* ΔG* and K are calculated from the TGA curve using Coats-Red fern method. The all prepared complexes were assayed for antibacterial (Escherichia coli and Staphylococcus aureus) activities by disc diffusion method. The results indicate that all tested ligand and complexes show antibacterial activity against E. coli and S aureus, as gram negative and positive bacteria.