The present paper overviews our recent experimental and theoretical results concerning the catalytic properties of nanosized rhodium and platinum facets in the presence of an external electric field. We first show that field ion microcopy (FIM) experiments along with corresponding density functional theory (DFT) calculations strongly indicate that a positive field value promotes the oxidation of a rhodium field emitter tip. We also demonstrate that the catalytic oscillatory nanopatterns, as observed when H(2) and O(2) are exposed on a rhodium field emitter tip, find their origin in the different catalytic properties of all the nanofacets that are simultaneously exposed at the tip's surface. In the case of platinum field emitter tips, the dependence of dissociation barrier of NO on the external electric field is examined with INT and compared to experimental results. Corresponding calculations on Pt are done for the (NO)(2) dimer. (C) 2010 Elsevier B.V. All rights reserved.