My mother recently stumbled upon this mix when she was trying to remove stains from some laundry. When just the peroxide didn't work, she sprayed on some Easy Off, and the stain disappeared. Now she uses this method regularly, and I'm worried that it might be toxic or something. I just want to make sure she isn't poisoning herself.
Chemically, we are talking about mixing hydrogen peroxide with sodium hydroxide. They will react to form sodium hydroperoxide, but the latter is not as good an oxidizing agent as hydrogen peroxide, and a weaker base than sodium hydroxide. Probably the added base helps to dissolve some components of the stain. I don't see this as risky, especially if it is on a small scale (spraying laundry), and uses 3% peroxide, rather than mixing them in bulk. Note: With hydrogen peroxide, you have to watch out because some metal ions catalyze its decomposition to oxygen and water.
I accidentally stumbled across this question. I once had a coworker clean a toilet with bleach and 409. The tragedy was he knew better and yet no one was injured. The man was smart but his thin stress management had a way of making things less clear headed when making everyday decisions.
I had to do OSHA 10 and OSHA 30 for work many years later. I realize such training is not much but it is something that made me want to check carefully as I make decisions. I have watched different people not check or measure twice to cut once or some such decision making process.
That said, in my opinion oven cleaners are harcore effective. I can't say what the oven cleaner in question was made of because I wasn't there. I want to comment on what @iad22agp wrote because it gave me the chills.
If a cleaner made with lye or sodium hydroxide is used or within splashing distance it sounds like extra care should be made to keep hydrogen peroxide very far away. I am not a chemist but I can read MSDS cautionary info. According to the California Fatality Assessment and Control Evaluation report below, posted by the CDC/NIOSH, a "mixture of sodium hydroxide and hydrogen peroxide produces a strong oxidizer called sodium peroxide and can result in an exothermic mist from the onset of high temperatures and heat from the decomposition of incompatible mixtures causing a severe thermal hazard."
The man who died must have experienced a horror show as he passed... I realize the FACE report is not an MSDS for either product but it seems important to consider when cleaning with chemicals in the way described by the OP's question. I realize that industrial chemicals are more dangerous than domestic cleaning products but being extra careful beats dying every time.