Pd(II) complexes of the form [PdLNH3] (where L = N-salicylidene-o-aminophenol (L1), N-(5-methoxysalicylidene-o-aminophenol) (L2) and N-(2-hydroxy-1-naphthalidene)-o-aminophenol) (L3) containing ammonia and ONO tridentate Schiff bases were synthesized. These complexes were characterized by elemental analysis, infrared, ultraviolet-visible, proton and carbon-13 spectroscopies. The NMR spectra showed that the Schiff bases coordinated to the palladium(II) ion through the two deprotonated phenolic oxygen and azomethine nitrogen atoms. The presence of ammonia molecules in these complexes were indicated by the IR and 1H NMR spectra. The spectral data suggested a square planar geometry for the complexes. The biological studies revealed that the complexes displayed better antibacterial and antioxidant activities than the parent Schiff bases.