Superoxide, and its derivatives hydrogen peroxide, hydrogen peroxide, and peroxynitrite, play an important role in aging and in several diseases, including cancer, diabetes, inflammation, neurodegenerative and vascular disorders. Increased level of reactive oxygen species leading to severe organ damage could also be a consequence of applied therapy, such as radiation therapy, chemotherapy,reperfusion after ischemia, or transplantation. A new approach to protect normal tissues without jeopardizing the efficacy of treatment may be to apply specific catalytic antioxidants as adjuncts to the therapy. In this review a number of synthetic low-molecular-weight agents are discussed that may be used as mimetics of superoxide dismutase enzymes (SODm) to treat diseases of various etiologies and to protect healthy tissues during therapy.