H2[PtCl6] + H2C2O4 → H2[PtCl4] + 2CO2 + 2HCl
Hydrogen hexachloridoplatinate(IV) react with oxalic acid to produce hydrogen tetrachloridoplatinate(II), carbon dioxide and hydrogen chloride. Oxalic acid - saturated solution. This reaction slowly takes place at a temperature near 0°C.