We present a case of an adult who suffered an apparent stroke shortly after an accidental ingestion of concentrated hydrogen peroxide. Complete neurologic recovery occurred quickly with hyperbaric therapy. Hydrogen peroxide can produce acute gas embolism. Hyperbaric therapy is the definitive treatment for gas embolism from hydrogen peroxide ingestion as it is for all other causes of acute gas embolism. This is the first case reported in the literature of hyperbaric therapy used successfully to treat cerebral gas embolism caused by hydrogen peroxide.