The transport characteristics of alpha-Ag1-xCuxI and alpha-AgI1-xClx solid solutions have been studied using molecular dynamics (MD) simulations. The cation diffusion coefficient decreases with increasing dopant (copper or chlorine) concentration. The results are in good agreement with the electric conductivity experimental data. The Cu composition dependence of the diffusion activation energy shows a maximum at the Cu content of x approximate to 0.15 for non-stoichiometric phases of alpha-Ag1-xCuxI. The calculated values of the cation transport numbers are in a good agreement with the experimental data. (C) 2003 Published by Elsevier Science B.V.