When aluminium hydroxide, oxalic acid, and potassium oxalate react, the products formed are aluminium oxalate and water. The chemical reaction can be represented as follows:

2Al(OH)3 + 3H2C2O4 + K2C2O4 → Al2(C2O4)3 + 6H2O

In this reaction, aluminium hydroxide reacts with oxalic acid to form aluminium oxalate, while potassium oxalate acts as a spectator ion and does not participate in the reaction. The product, aluminium oxalate, is an insoluble compound that precipitates out of the solution.