The rate constant of electron-hole recombination in the bulk of a rutile TiO2 single crystal was estimated to be k(rec) = 5 x 10(-13) cm (3) s (1) through sub-nanosecond time-resolved transient absorption spectroscopy. This value is more than four orders of magnitude smaller than the diffusion-limited rate constant (k(rec)(diff) = 1.4 x 10(-8) cm(-3) s(-1)) for a rutile TiO2 crystal, suggesting low recombination reactivity between electrons and holes in the crystal. (C) 2008 Elsevier B.V. All rights reserved.