Results for the measurement of the diffusion coefficients of Tl(0) in a Tl/Hg amalgam (D(H9)), and Tl(+) in 1.0 M KF aqueous solution (D(aq)) are presented. The values of D(Hg) = (1.2 +/- 0.1) X 10(-5) cm(2) s(-1) and D(aq) = (2.4 +/- 0.2) x 10-5 cm(2) s(-1) at 22 +/- 1 degrees C are obtained by means of comparison of experimental deposition and stripping chronoamperometric transients with theoretical simulations for a 12.5 pm radius hemispherical mercury drop in which Tl is first deposited and then stripped. (c) 2008 Elsevier B.V. All rights reserved.