The diffusion of Be in InGaAs grown by gas source molecular beam epitaxy has been studied. The observed secondary ion mass spectrometry Be profiles, obtained for annealing cycles with a temperature range of 700-900degreesC, could be explained considering several forms of kick-out mechanism. The beryllium diffusion models in InGaAs have been obtained without a priori hypothesis on interstitial beryllium and self-interstitial. Moreover, the fitting procedure of experimental data has been described precisely. We conclude that two kick-out mechanisms lead to similar fittings of experimental profiles and may not be distinguishable using our experimental conditions. (C) 2003 Elsevier Science B.V. All rights reserved.