Uniform single-crystalline ZnO nanodisks and nanowires (thick and thin nanowires) with well-developed facets have been synthesized hydrothermally. It is demonstrated that the unique ZnO nanodisks with a high (0 0 0 1) facet population and small surface area show the best photocatalytic activity among the samples. All the samples are in the same comparable dimension and surface area regime and the design of nanodisk and nanowire reduce the effect of unwanted facet effect to a degree as minimum as possible when catalytic activity of (0 0 0 1) and {1 0 (1) over bar 0} facets are compared. The results indicate that photocatalytic activity strongly depend on specific crystal planes. (C) 2009 Elsevier B. V. All rights reserved.