In this paper nanocrystalline mesoporous iron-based high temperature water gas shift catalysts were prepared by coprecipitation method in water-in-oil (W/O) microemulsion. The prepared samples were characterized by using X-ray diffraction (XRD), N-2 adsorption (BET), temperature-programmed reduction (TPR), Fourier transform infrared spectroscopy (FTIR), transmission and scanning electron microscopies (TEM, SEM) techniques. The results revealed that the Fe2O3 possessed low specific surface area and catalytic activity in high temperature water gas shift reaction. The addition of copper to Fe2O3 favored the active phase formation and significantly decreased the reduction temperature of hematite to magnetite and consequently improved the catalytic activity of Fe2O3. The incorporation of chromium in hematite increased the surface area and catalytic activity of Fe2O3. The results also showed that the prepared Fe-Cr-Cu catalyst showed higher activity than the commercial catalyst. In addition, the effects of GHSV, steam/gas ratio, and calcination temperature were investigated on the catalytic performance of Fe-Cr-Cu catalyst. (C) 2016 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.