Hierarchically mesoporous-macroporous titanium dioxide (MMTD) was synthesized by the hydrolysis of tetrabutyl titanate in the absence of surfactant and autoclaving at 60 A degrees C, which exhibits a porous hierarchy of wormhole-like mesostructure in the framework of macrochannels. Different contents of CuO nanoparticles were supported on the MMTD by a deposition-precipitation (DP) method, retaining the high surface areas and hierarchical porosity. The prepared MMTD support and the resulting CuO/MMTD nanocatalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), N-2 adsorption analysis, temperature-programmed reduction (TPR), and X-ray photoelectron spectroscopy (XPS) techniques. Their catalytic behavior for low-temperature CO oxidation was studied by using a microreactor-GC system, and the CuO/MMTD catalyst with 8 wt% CuO content and calcined at 400 A degrees C was found to have the highest catalytic activity. The catalytic activity depended on the CuO loading amount, the precalcination temperature, the meso-macroporous framework, the surface area, and the particle size of the CuO/MMTD catalysts.