1-(2-Hydroxyphenyl)-3-propane-1, 3-diones 4(L A -L B ) and its metal complexes 5(a-e) have been newly synthesized from substituted 2-hydroxyacetophenones 1(A-B) and aromatic acids 2(A-B) under ultrasound irradiation method at low temperature. These compounds were characterized by FT-IR, UV-Vis., 1 H-NMR, 13 C-NMR, mass spectroscopy and magnetic measurement. The stoichiometry of the complexes was found 1:2 (metal:ligand). The physicochemical data suggested octahedral geometry for all the complexes. The ligands 4(L A -L B ) and their metal complexes 5(a-e) were screened for in vitro antibacterial activity against S. aureus, B. subtilis, E. coli and P. aeruginosa compared with tetracycline and chloramphenicol as a standard drugs. The results are in good agreement with respect to activity of free ligand and its metal complexes. Reactions under ultrasonic irradiation had improved yield.