In this work, we compare the activity of unsupported and monoclinic zirconia supported nickel ferrites, calcined at two different temperatures, for solar hydrogen production by two-step water-splitting thermochemical cycles at low thermal reduction temperature. Commercial nickel ferrite, both as-received and calcined in the laboratory, as well as laboratory made supported NiFe(2)O(4), are employed for this purpose. The samples leading to higher hydrogen yields, averaged over three cycles, are those calcined at 700 degrees C in each group (supported and unsupported) of materials. The comparison of the two groups shows that higher chemical yields are obtained with the supported ferrites due to better utilisation of the active material. Therefore, the highest activity is obtained with ZrO(2)-supported NiFe(2)O(4) calcined at 700 degrees C. (C) 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.