The reaction between formaldehyde and potassium permanganate is a redox reaction, where formaldehyde acts as the reducing agent and potassium permanganate acts as the oxidizing agent. The products of the reaction are potassium formate, manganese dioxide, and water. The overall reaction can be represented as follows:

$$5HCHO + 2KMnO_4 + 3H_2SO_4 → 5HCOOK + 2MnSO_4 + 8H_2O + 2CO_2$$

In this reaction, formaldehyde is oxidized from a +1 oxidation state to a +2 oxidation state in potassium formate. Potassium permanganate is reduced from a +7 oxidation state to a +2 oxidation state in manganese sulfate. The reaction is typically carried out in acidic conditions using sulfuric acid as a catalyst.