Antioxidants are receiving increased attention for their potential effects in the prevention of chronic and degenerative diseases such as cancer and cardiovascular disease as well as aging.1 These health promotion effects may be related to components in the foods with antioxident activity.3 There are many methods developed for the determination of antioxidant capacity. However the biggest problem appears to be the lack of a validated assay of general applicability that can reliably measure the antioxidant capacity of foods. The primary action of antioxidants is to mop up free radicals. Muonium being a free radical with the least steric requirements would be able to probe this without the inconsistancies inherent in the use of larger probe probe radicals. The present experiment is to explore the possibility of devising a muonium reactivity based antioxidant capacity measurement.