Two series of WOx-CeO2 catalysts containing 10, 12, and 15 wt % W were prepared by co-precipitation and incipient wetness impregnation using a reported procedure. WOx-Nb2O5 catalysts with the same amount of W were prepared by co-precipitation starting from an aqueous solution of ammonium niobium oxalate and ammonium metatungstate with ammonia, until reaching pH 7. After calcining for 3 h in static air at 973 K, the deactivation of the catalysts was investigated using isomerization of hexane as probe reaction at temperatures in the range 393-513 K, both in the absence and in the presence of hydrogen. In-situ Raman spectra during deactivation were recorded as well. The deactivation rate was fitted by an empirical Voorhies equation: R = m t(-n), where the values of n correlated very well with the mass loss determined from TG analysis.