Diffusion of Fe in CIGS was investigated on solar-grade CIGS layers using radiotracer sputter-profiling of (59)Fe or in-depth secondary ion mass spectrometry (SIMS) of natural iron isotopes. In both cases natural or radioactively labelled iron was deposited on the front-surface of CIGS/Mo/float-glass samples. Fe penetration profiles were measured after isothermal annealing in a lamp oven at different temperatures. A diffusivity of 4 x 10(-13) cm(2) s(-1) was deduced from Gaussian-type SIMS profiles originating from annealing at 300 degrees C. It was found that pronounced sputter-broadening effects may complicate the interpretation of the diffusion profiles. (C) 2008 Elsevier B.V. All rights reserved.