The letter reports a single-step method for fabrication of metal nanoparticle loaded mesoporous alumina through anodizing of a commercial aluminum alloy. The metal nanoparticles, with short dimensions of 2-4 nm and aspect ratios up to 8, display crystalline structures and are evenly dispersed in mesoporous alumina. The approach can easily be implemented on a large scale and extended to other alloy systems consisting of a valve metal and different alloying elements with Gibbs free energy of oxide formation less negative than that of the valve metal, benefiting nanoarchitecture design and nanostructure synthesis for applications in catalysis, ion exchange, sensing, etc. (C) 2011 The Electrochemical Society. [DOI: 10.1149/2.019201esl] All rights reserved.