The macroporous supported Cu–V oxide prepared by a novel dissolution–reprecipitation process was found to be the first example of a promising substitute of Pt catalysts for sulfuric acid decomposition at moderate temperatures (∼600 °C), which is required in solar thermochemical hydrogen production. Stepwise impregnation of Cu­(NO3)2 and NH4VO3 onto 3-D ordered mesoporous SiO2, and subsequent heating at 650 °C yielded the deposition of copper pyrovanadate (Cu2V2O7, melting point: 780 °C) not only in mesopores but also on the external surface. Thermal aging at 800 °C caused the congruent melting of Cu2V2O7 followed by smooth penetration of the melt into mesopores and homogeneous covering of cavity walls. Because of the solubility of SiO2 into the molten vanadate, dissolution–reprecipitation should be equilibrated to allow substantial structural conversion from mesoporous to macroporous SiO2 frameworks. The resulting macroporous catalyst consisting of highly dispersed thin layers of active Cu2V2O7 is considered efficient for catalytic reactions and the mass transfer of reactants and products in the presence of high-concentration vapors.