The wall-to-fluid mass transfer coefficient was obtained from coated wall dissolution experiments, for water flow through fixed beds of spheres with tube-to-particle diameter ratios of 2.9-11.6, and for particle Reynolds number (Re) in the range 3-200. The coefficients, in the form of dimensionless Sherwood numbers (Sh(wf)), were shown to approach a nonzero limit as Re --> 0. The data were well-represented by the equation Sh(wf) = 15.0 + 0.63Sc(1/3) Re-0.57. Qualitative differences were shown between the behavior of the wall coefficients Sh(wf), which approached a constant value as Re decreased, and the overall coefficients Sh(ov), which approached zero as Re decreased. (C) 2003 Elsevier Science Ltd. All rights reserved.