I've been to every store and even some farmacias and no one has it. It's driving me nuts..Anyone know where I can find some in Madrid?

I had the same problem in Barcelona several years ago. I tried several farmacias and no one seemed to have it under the name peroxida, but when I gave them a slip of paper with the chemical name h2o2 they immediately went to the back drawers and got it.

Thank you!!! I've been on a little hunt for it for a few months now. I will ask them for the chemical formula (studied Chemistry...should have known that one!)