The invention relates to compounds which are orally bioavailable water soluble metalloporphyrins. These compounds, e.g. represented by Structural Formula (I): wherein R1 and R2 are each independently lower alkyl, cycloalkyl, halogen substituted alkyl or substituted or unsubstituted phenyl groups, are synthetic catalytic scavengers of reactive oxygen chemical species. The invention also relates to pharmaceutical compositions comprising these compounds and to methods of use of these compounds for preventing or arresting free radical associated diseases or conditions.