Nanocomposite copper-ceria catalysts are provided, which comprise 
copper oxide nanoparticles, 
copper nanoparticles, or a mixture thereof combined with ceria nanoparticles. Methods for making such catalysts are also provided, which involve the steps of (i) combining ceria nanoparticles in an 
aqueous suspension with copper 2,4-pentanedionate to form a 
slurry; (ii) heating the 
slurry formed in step (i) under an 
inert gas 
atmosphere or an 
oxygen-
argon atmosphere, at a temperature and for a time sufficient to cause 
decomposition of the copper 2,4-pentanedionate to form copper nanoparticles and / or 
copper oxide nanoparticles that are combined with the ceria nanoparticles; and (iii) optionally, subjecting the product formed in step (ii) to a heat treatment process under conditions effective to convert at least some of the copper nanoparticles to 
copper oxide nanoparticles. The 
nanocomposite copper-ceria catalysts are useful for low-temperature and near-ambient temperature 
catalysis, such as the oxidation of 
carbon monoxide, the reduction of 
nitric oxide and the conversion of hydrocarbons. The 
nanocomposite copper-ceria catalysts have a variety of potential applications, for example, 
in vehicle exhaust emission systems of automobiles and diesel engines, cold starting of automobile engine, 
fuel cells, lasers, 
hydrocarbon conversion reactors, air filters for the conversion of 
carbon monoxide and / or indoor volatile organic compounds, and smoking articles.