I happened to come to this site by chance. I was checking solubilities of a few compounds I am considering mixing and came across a thread where people were discussing sodium percarbonate and hydrogen peroxide. Someone mentioned about stabilization of the H2O2 but no one could remember what chemicals to use for that. << Mentor Note: Link to the old thread is added here >> https://www.physicsforums.com/threads/h2o2-in-h20-stability.278442/ I have done this in the past and currently work with it now. You use both sodium stanate and phosphoric acid at about 0.1% for each in hydrogen peroxide that approaches 8%. At lower concentration the breakdown is much slower. Even with the stabilizers it will still break down. My experience has shown me that a 7.9% hydrogen peroxide solution will break down to 7.1% over 5 years when it is stored properly in an opaque container. You also need to remember that during the break down there is continual off-gassing of oxygen (H2O2 breaks down to H2O) so you need to store it with a vented cap to relieve the pressure that builds up. As for using sodium percarbonate as a source for hydrogen peroxide, good idea, I do it myself but be sure if you are mixing it with other compounds check your solubility and keep in mind that the other part of sp is Na-carbonate which will drive your pH up. Do not use the phosphoric acid to control the pH with the Na-percarbonate, it will react violently. Instead use citric acid or boric acid depending on your application. Okay, that's my 2 cents for the day.