A sensitive and relatively selective indirect differential-pulse polarographic (DPP) method for the determination of Pt^II is described. The method is based on the chemical reaction between metallic Hg and divalent Pt to form a stoicheiometric amount of Hg^I ions. The Hg^I ions are oxidised further to Hg^II and monitored by DPP after complexation with salicylaldehyde thiosemicarbazone at pH 4.7. Various experimental parameters were studied. The range of application is between 0.4 and 610 µg ml^–1 of Pt^II. A statistical evaluation of the experimental results is reported. The method was applied to the determination of Pt^II in synthetic solutions of various compositions.