Diffusion of In-114m in polycrystalline Cu(In-0.7, Ga-0.3)Se-2 thin films has been investigated by measuring radiotracer activity depth profiles by means of ion sputtering. The measurements were carried out in the temperature range between 523 K and 723 K. The obtained diffusivities vary between 7.3 x 10(-17) cm(2) s(-1) at 523 K and 1.4 x 10(-12)cm(2) s(-1) at 723 K with an activation energy of (1.42 +/- 0.09) eV. The grain boundary diffusivities in this temperature range vary between 1.0 x 10(-12) cm(2) s(-1) at 523 K and 2.9 x 10(-8) cm(2) s(-1) at 723 K and a first order-of-magnitude estimation of the activation energy for the grain boundary diffusion yields a value of (1.04 +/- 0.18) eV. (C) 2015 Elsevier B.V. All rights reserved.