An approach to identify mass diffusion coefficients (D) is presented, and applied to the case of a slab. It was based on a numerical exploitation of the concentration profiles to estimate the mass fluxes. The effect of the quality of the experimental data (spatial resolution, Delta(z) over bar, temporal resolution, Delta Fo, of the concentration profiles, sampling) on the bias and sensitivity of the method was studied thanks to the use of simulated data (Fo is an element of [0,2]), to which could be added Gaussian noise. Estimated D value were compared with the true solution (the one used for generating the simulated concentration data). The errors on D are large at low Fo < 0.2. But for Fo > 0.2, D can be estimated with less than 1% of bias if Delta Fo < 0.1 and Delta(z) over bar < 0.2. Space resolution had a minor effect. Although rough, the numerical procedure adopted in this paper revealed especially suitable for modern techniques of concentration measurements exhibiting high-accuracy (< 1%). (c) 2004 Elsevier Ltd. All rights reserved.