When manganese dioxide is added to a hydrogen peroxide solution in water is catalyzes the breakdown of the hydrogen peroxide into water and oxygen gas. You can find the order of reaction by measuring the time taken for a small volume of oxygen to be given off at the beginning of the reaction for a variety of different concentrations of hydrogen peroxide solution and then processing the results. The principle of operation and manufacturing techniques are introduced for a calorimetric h 2 o 2 gas sensor based on porous mno 2.