Potassium hexachloroplatinate is the inorganic compound with the formula K₂PtCl₆. It is a yellow solid that is a poorly soluble in water. The salt features the hexachloroplatinate(IV) dianion, which has octahedral coordination geometry.

The precipitation of this compound from solutions of hexachloroplatinic acid has been used for the determination of potassium by gravimetric analysis. It is an intermediate in the recovery of platinum from wastes.

Using salt metathesis reactions, potassium hexachloroplatinate is converted to a variety of quaternary ammonium and related lipophilic salts. These include tetrabutylammonium salt (NBu₄)₂PtCl₆, which has been investigated as a catalyst.

Reduction of potassium hexachloroplatinate with hydrazine dihydrochloride gives the corresponding tetrachloroplatinate salt.

Potassium hexachloroplatinate reacts with aqueous ammonia to give chloropentammineplatinum chloride:

Dust containing potassium hexachloroplatinate can be highly allergenic. "Symptoms range from irritation of skin and mucous membranes to life-threatening attacks of asthma."