An extensive series of supported WO 3/ZrO x (OH) 4−2 x catalysts (WZrOH) were synthesized by standard aqueous impregnation of ammonium metatungstate into an amorphous ZrO x (OH) 4−2 x metastable support, followed by high-temperature calcination (at 773–1173 K). The supported WZrOH catalysts were also compared with well-defined model supported WO 3/ZrO 2 catalysts (WZrO 2) consisting of a thermally stable crystalline m-ZrO 2 support. Both series of supported tungsten oxide catalysts were physically characterized (by XRD, XPS, TEM, in situ Raman, and in situ UV–vis spectroscopy) and chemically probed by methanol dehydration (i.e., TPSR spectroscopy and steady-state catalytic studies). Monolayer surface WO x coverage was found to occur at ∼4.5–5 W-atoms/nm 2 for both catalytic systems. Whereas the dehydrated model supported WZrO 2 series contained only surface WO x species below monolayer coverage, the dehydrated supported WZrOH series had the same surface WO x species, as well as some Zr-stabilized distorted WO 3 nanoparticles (NPs). Above monolayer coverage, the model supported WZrO 2 catalysts contained only ordered crystalline WO 3 NPs, but the supported WZrOH catalysts had both ordered WO 3 NPs and Zr-stabilized distorted WO 3 NPs. The comparative methanol dehydration to dimethyl ether acidity study revealed that the Zr-stabilized distorted WO 3 NPs were the catalytic active sites in supported WZrOH catalysts. These findings represent a new model for the origin of the enhanced solid acidity of supported WZrOH catalysts.