The influence of the concentration dependence of the diffusion coefficient is introduced in the theoretical analysis of lithium insertion by transient electrochemical techniques. The model is based on the numerical integration of the diffusion equation. The procedure proves to be useful to study the behaviour of systems involving phase transition processes in which a large change of the chemical potential induces an important contribution to the diffusion flux. In this case, the use of the complementary error function provides an efficient mean to describe the thermodynamic and kinetic properties of the system. (c) 2005 Elsevier B.V. All rights reserved.