We demonstrated for the first time that single-crystalline Se nanorods (NRs), prepared with a facile chemical reduction approach at room temperature. may display noticeable catalytic activities toward methylene blue degradation in dark environment after subjected to a short period of irradiation. Such capability of photocatalysis in the dark for Se NRs was attributed to the memory effect related to pre-irradiation treatment. The result of spin-trapping electron paramagnetic resonance measurement suggests that a sustained supply of center dot OH radicals could be attained for Se NRs upon the cease of irradiation, which is accountable for the memory photocatalytic effect as revealed in the dark. As compared to the commercial P-25 TiO2 powder and Se nanoparticles, the as-synthesized Se NRs exhibited superior photocatalytic performance under UV illumination, demonstrating their potential as active photocatalysts in relevant redox reactions. Furthermore, the recycling test reveals that Se NRs could be promisingly utilized in the long-term course of photocatalysis. The present Se NRs may find potential use for unique photocatalytic applications, in which typical photocatalysis prevails under light illumination, while memory photocatalytic effect takes over when irradiation is interrupted. (C) 2011 Elsevier B.V. All rights reserved.