We studied the post-growth annealing of CdZnTe crystals in a temperature-gradient field and compared the changes of Te inclusions in CdZnTe crystals before and after annealing. The infrared (IR) transmission microscopy shows that Te inclusions can migrate towards the high-temperature end and leave some smaller dark spots behind. These dark spots may be voids within the original inclusions left behind after the migration of the Terich solid. Such thermo-migration depends on the specific locations of the Te inclusions within the CdZnTe matrix. Grain boundaries could have a strong trapping effect on the migration of Te inclusions, probablythrough the high density of dislocation networks in the grain- boundary region. In addition, we also observed new Te inclusions in the grain-boundary regions, which were formed during the annealing process. This phenomenon is attributed to the fast diffusion and gettering behavior of excess Te atoms, or possibly Cd vacancies, along the grain boundaries. (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)