Nanocrystalline ceria-zirconia(-lanthana) based fluorite-like oxide solid solutions prepared via polymerized complex precursor route, with or without supported Pt, have been used for detailed transient kinetic studies of water gas shift (WGS) and partial oxidation of methane (POM) at 650 degrees C and short (similar to 10(-2) s) contact times. It was shown that high bulk oxygen mobility and storage capacity characterizing nanocrystalline structure of ceria-zirconia and regulated by the partial substitution of Ce for La are responsible for vigorous CO2 evolution during start-up regimes. At the same time, it favors preferential methane and CO oxidation on Pt particles, thus revealing a crucial importance of Pt cluster structure. (C) 2014 Elsevier B.V. All rights reserved.