There are a lot of places on the internet that sell 35% hydrogen peroxide. Before you take it be sure to read the precautions at http://stopcancer.com/oxygen.htm . I bought mine from Garden of Eden at http://www.dfwx.com/h2o2.htm I got their other version of hydrogen peroxide called Jutrian Rx. It is supposed to have lots of minerals in it too.
You can read all about it at the site. I think either of these places or a lot of other places on the net could be a good place to buy it but since I bought mine from one place and have personally met and talked to Dr. Donsbach that are the two places that come to mind. Very few health food places carry it and you can figure out why when you read all the precautions that are on both of these sites.

Good Luck