NOx storage and reduction with H(3)PW(12)O(40)(.)6H(2)O (HPW) supported on TixZr1-xO4 (0 <= x <= 1) were measured under representative HPW at 170 degrees C) and depends on support Zr/Ti molar ratio. NOx lean-gas mixture conditions. Storage capacity is high (28 mg of NOx g(HPW)(-1) reduction highly depends on reducing mixture (CO, H-2 or H-2 + CO), on the presence of noble metal (platinum) and support, and on the operating conditions (long or short cycles). H-2 + CO mixture proved to be effective for NOx reduction into N-2 even if low activity was detected for each gas separately. With short cycles of lean/rich (2/1 min) at 250 degrees C, (HPW-Pt)/TixZr1-xO4 (with Zr/Ti molar ratio equal to 0.5) is significantly more active than unsupported HPW-Pt, delivering upto 40% NOx reduction into N-2 with 75% of NOx storage efficiency. Experimental results evidence the kinetic coupling between NO2 reduction and CO oxidation during NOx reduction. The combination of NOx storage and reduction concept with a multifuctional catalyst is very promising. (c) 2005 Elsevier B.V. All rights reserved.