Transition metals play an important role in wide variety of biological processes in living system. Exposure to toxic metals, specifically arsenic (As) and chromium (Cr), has been associated with inflammation, cellular damage, and cardiovascular diseases as a result of As/Cr-mediated oxidative stress. We investigated the characteristics of the oat bran protein isolates (OBPIs) and the oat bran protein hydrolysates (OBPHs), their ability to reduce the toxicity of arsenic and chromium as well as their radical scavenging properties. Results showed that OBPIs possessed higher protein contents (80%), molecular weight (MW > 20kDa) and levels of aromatic amino acid residue than OBPHs. Hydrolysis increased peroxyl radical scavenging activities (ORAC) but lowered hydroxyl radical (HO•) potentials while only minor changes were observed in the superoxide anion radical scavenging power. Data showed that OBPI and OBPH were able to reduce toxicity of arsenic and chromium in food.