Mixed ligand complexes of the formula [M (phen) bdt] where M= Pd (II) or Pt(II), phen =1,10phenanthroline and bdt =1,2-benzenedithiolate have been synthesized and studied as photosensitizers of singlet molecular oxygen (1O2) production. It was observed that, Pt (II) complex shows a better photosensitizing ability as compared to its Pd (II) analogue. However, both Pd (II) and Pt (II) complexes act as chemical quenchers of 1 O2, resulting in their photo oxidation shown by decay of the respective complex. ThusPt (II) complex undergoes self-sensitized photo oxidation by 1O2. The solvent dependence of this reaction is undertaken by performing the experiment using pure DMF (dimethyl form amide) and 10% H2O in DMF as solvent. The comparison of rate of decay of the Pt (II) and Pd (II) complexes show enhancement of the reaction in presence of water. The decay of the complex was monitored by recording the difference absorption spectra of the complex in the visible region after definite irradiation times. Involvement of 1O2 is further supported by quenching studies of this reaction using NaN3 as physical quencher of 1O2.