Copper and nickel carboxylates of castor seed oil were prepared by metathesis in aqueous ethanol.The FTIR spectra of the carboxylates are characterized by two asymmetric vibrations of the carboxylate group and two symmetric vibrations.For Cu carboxylate,the values are 1594 &1532cm
-1 and 1458 & 1409cm
-1while those of Ni carboxylate were observed at 1561 & 1513cm
-1 and 1469 & 1412cm
-1 respectively indicating that the carboxylates existed as bridging bidentate structure and confirmed their formation. The carboxylates were calcinated in muffle furnace at 400
oC to obtain blackish derivatives. Antimicrobial activities of the carboxylates and their calcinated derivatives were assayed using modified Kirby Bauer disc diffusion method against two groups of medically implicated bacterial species, viz: Gram positive organisms (
Staphylococcus aureus
and
Streptococcus faecalis
,) and Gram negative organisms (
Pseudomonas fluorescence
,
Salmonella thypii
,
Klebsiella pneumonia
and
Proteus mirabilis
). It was observed that the antimicrobial potencies of the carboxylates and their derivatives compared favourably with the standard antibiotics used for the assay. However, calcinated derivative of Ni carboxylate showed a quite significant increase in the antimicrobial potency against both gram negative andgram positive microorganisms when compared with its carboxylate.