Decomposition of hydrogen peroxide catalysed by manganese (IV) oxide. Hydrogen peroxide (H2O2) is unstable, and naturally decomposes very slowly at room temperature, producing water and oxygen gas. The speed of this decomposition can be greatly increased by a catalyst, however. Most transition metals and their compounds can perform this function. Some of the manganese forms ions in solution, which undergo redox reactions with the peroxide that form species that react further to produce the water and oxygen, and produce manganese dioxide again.