Metal nanopowders are common and frequently employed in industry. Iron is mostly applied in high-performance magnetic materials and pollutants treatment for groundwater. Zinc is widely used in brass, bronze, die casting metal, alloys, rubber, and paints, etc. Nonetheless, some disasters induced by metal powders are due to the lack of related safety information. In this study, we applied differential scanning calorimetry (DSC) and used thermal analysis software to evaluate the related thermal safety information, such as exothermic onset temperature (T-o), peak of temperature (T-p), and heat of reaction (Delta H). The nano iron powder experimental results of T-o were 140-150 degrees C, 148-158 degrees C, and 141-149 degrees C for 15 nm, 35 nm, and 65 nm, respectively. The Delta H was larger than 3900 J/g, 5000 J/g, and 3900 J/g for 15 nm, 35 nm, and 65 nm, respectively. Safety information can benefit the relevant metal powders industries for preventing accidents from occurring. (C) 2013 Elsevier B.V. All rights reserved.