Chemical-looping processes are considered as a suitable way to produce hydrogen and syngas. The major advantage of the chemical looping hydrogen production processes is that the heat needed for converting CH4 to H-2 and CO is supplied without costly oxygen production and without mixing of air with carbon containing fuel gases. One key issue with the chemical looping concept is the choice of the suitable oxygen-carrier material and its oxidation and reduction behavior as well as cost, availability, performance, environmental and safety aspects. This review is focused on the preparation, characterization and performance of various types of oxygen carriers for hydrogen production via various chemical looping processes. (C) 2016 Elsevier Ltd. All rights reserved.