A series of CexZr1-x O-2 mixed-oxide- supported Ru catalysts were unprecedentedly evaluated in the catalytic wet air oxidation (CWAO) of 2-chlorophenol (2-CP) solutions (2 g L-1). They were shown to exhibit higher performances than the corresponding CeO2 or ZrO2-supported catalysts. The ceria-zirconia solid solution structure appeared to be crucial for the higher activity of the 3 wt.% Ru/CexZr1-xO2 catalysts. After introduction of praseodymium or neodymium in the CexZr1-xO2 lattice, the activity of the 3 wt.% Ru/CexZr1-xO2 catalysts was further improved. Pr was shown to have a greater effect than Nd, especially at low Pr concentration. Further investigations indicated that CexZr1-xO2 solid solutions loaded Ru catalysts could maintain outstanding catalytic performances even at low temperature (393 K) and low pressure (3 MPa). (C) 2007 Elsevier B.V. All rights reserved.