Acetone thiosemicarbazone (ACTSC) a very versatile Schiff base ligand reacted with some transition metals forming co-ordination complexes. These solid complexes have been isolated and characterized on the basis of elemental analysis and spectroscopic studies (UV-Vis, FT-IR and 1H-NMR). The infrared spectra of the complexes revealed bands at (736-864 nm) and (1608-1627 nm) attributed to (>C=S) and (>C=N) respectively. These bands experienced a negative shift when compared to the spectral of the parent ligand. The electronic absorption spectra of the ligand shows a band around (198-200 nm) corresponding to the NH-C=S group, also a band due to the C=N chromophore in the spectrum of ligand at 294 nm (π-π∗ transition) undergo bathochromic shift to (310-336 nm) in the spectra of metal complexes. The ligand and the corresponding metal complexes were screened for their antifungal activities against Aspergillus niger, Penicillium species, Rhizopus and Candida albicans using adapted qualitative diffusimetric method. The most active complex is Cu(ACNT)2Cl2 with (27.67±0.58 mm) against Rhizopus. The activities of the metal complexes were found to be greater than that of the ligand. Toxicity effects of administration 50 mg/kg body weight of the control group showed that AST(20.67 ± 1.53 μ/L), ALT(22.33 ±2.08 μ/L), and ALP(30.67 ± 2.08 μ/L) which are quite significantly different (P< 0.05) from that of ACTSC which gave AST(25.67 ± 2.52 μ/L), ALT(27.67 ± 1.53 μ/L) and ALP(54.00 ± 3.05 μ/L) an indication of liver derangement. 25 and 50 mg/kg body weight of Ni(ACNT)2SO4, Zn(ACNT)2Cl2, Cu(ACNT)2Cl2 and Cu(ACNT)2SO4EtOH on the liver enzyme showed no significant difference (P≥ 0.05) when compared to the control group which is an indication of little or no toxicity. The study however showed that complexation of the ligand with metal ion increases the activity of the complexes and also reduces their toxicity level.