A series of W-Cu-Ce mixed oxide catalysts prepared by microemulsion was evaluated in the water-gas shift (WGS) reaction. At low temperatures (<350 degrees C), the total conversion of CO on the W-Cu-Ce systems was two times larger than on binary Cu-Ce mixed oxides which are well known catalysts for the WGS. In addition and in contrast with Cu-Ce, W-Cu-Ce catalysts were stable and no signs of deactivation were found after 10 h of reaction time. The rationale for the excellent catalytic performance presented by the W-Cu-Ce ternary oxide was elucidated from the viewpoint of a complete structural (e.g. analysis of the long and short range order) and redox behavior characterization using in situ, time-resolved X-ray diffraction (XRD) as well as X-ray absorption (XAS), infrared (diffuse reflectance Fourier transform DRIFTS) and Raman spectroscopies. From a single phase fluorite-type structure, the catalysts show significant structure/redox evolution under reaction conditions as a function of the W and Cu content. As it occurs in the parent Cu-Ce system, the dominant presence of metallic Cu and fluorite-type oxide phases is detected under reaction conditions for the ternary systems. An outstanding promotion of catalytic properties is nevertheless evidenced for samples with W content above 10 at.% and is shown to be related to the presence of oxidized W-Cu local entities. Such local entities, which are obviously characteristic of the ternary system, greatly enhance fluorite redox properties and play an interfacial role between the main metallic Cu and fluorite-type oxide phases. As a consequence of all these effects, incorporation of W into the initial material leads to efficient WGS catalysts, most promising for their application in the so-called low temperature region, e.g. below 350 degrees C. (c) 2012 Elsevier B.V. All rights reserved.