In this study, zero valent iron (ZVI) powders were generated by reducing iron oxide powders obtained from a pickling line in a transfer type reductor. The physical and chemical characteristic of the produced ZVI powders were analyzed by using instruments. Reaction activities of ZVI powders for decomposition of a methylene blue were evaluated. The mean size of ZVI powders increased and the specific surface area decreased with increasing reduction temperature due to sintering. The methylene blue decomposition rate increased with dose of ZVI powders. The ZVI powders generated by reducing iron oxide showed higher decomposition efficiencies than the commercial ZVI powders at all pH values tested in this study. Both non-commercial ZVIs showed a higher decomposition rate at a lower pH; (C) 2013 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.