We investigated the influence of methylviologen (MV2+), which accelerates the photoetching process used for controlling size distribution, on the photoluminescence (PL) properties of colloidal CdS quantum dots (QDs). A combination of the photoetching process and surface modification with a Cd(OH)(2) layer enabled us to prepare size-and surface-controlled CdS QDs. The efficiency of the photoetching process is extremely enhanced by the addition of MV2+. The temperature dependence of PL decay profiles indicates that MV2+ does not affect the PL properties of QDs. Consequently, the addition of MV2+ results in a highly efficient preparation of size-controlled CdS QDs without degradation of the PL efficiency. (C) 2008 Elsevier B.V. All rights reserved.