The complexes Mn(II), Ni(II), Cu(II) and Zn(H) ions with a N2O2 Schiff base derived from 1,4-diaminobutane and salicylaldehyde, N,N'-bis(salicylidene)-1,4-diaminobutane (LH2), have been prepared and characterized by elemental analyses, molar conductivities, spectral (IR, NMR, visible, UV) and magnetic moment measurements. Stability constants were measured by means of a conductometric method. Furthermore, the stability constants for complexation between ZnCl2, Cu(NO3)(2) and AgNO3 salts and the ligand in 80% dioxane-water and pure methanol were determined by conductance measurements. The magnitudes of these ion association constants are related to the nature of the solvation of the cation and the complexed cation. The mobilities of the complexes are also dependent, in part, upon solvation effects. The complexes Mn(II), Ni(II), Cu(II) and Zn(II) ions with the Schiff base have been evaluated for their antibacterial activity against rec(-)and rec(+) stains of Bacillus subtilis.