We present a rigorous approach for the shape design of supported metal nanoparticle catalysts morphologically identical to each other and epitaxially grown on strontium titanate substrates using electron beam lithography We predict the particle shapes using Wulff construction based on density functional theory calculations of surface energies Then according to the theoretical predictions we are able to tweak morphologies of the already produced nanocrystals by changing annealing conditions The ability to design produce and characterize the catalyst nanoparticles allows us to relate microscopic morphologies with macroscopic oxygen-reduction activities in perchloric acid [Komanicky et al J Am Chem Soc 131 (2009)5732] The unexpectedly high oxygen-reduction activities proportional to inactive (1 0 0) facets led us to suggest a model where the reaction intermediates can cross over to neighboring facets in nanoscale proximity (C) 2010 Elsevier Ltd All rights reserved