The 1,2,4-trioxane ring is a poorly studied hetcrocycle. Not many derivatives are known. However, the sole example found in nature, artemisinin (Qinghaosu), commands attention on account of its potent anti -malarial properties. We discuss new methodology for preparing a variety of 1,2,4-trioxanes. The basis of the method is the capture of zwitterionic peroxides by aldehydes. Precursors such as allylic hydroperoxides, peroxides, and 1,2- dioxetanes behave similarly and can be captured by aldehydes and ketones in intramolecular and intermolecular processes. The structures of many of the 1,2,4-trioxanes so obtained have been established by X-ray ana lysis. In addition, the chemistry of the trioxane ring is discussed, in particular the formation of 1,2-diol monoesters.