The microstructural properties of the beta-FeSi2/FeSi structure prepared from a molten salt have been characterized using transmission electron microscopy (TEM). The beta-FeSi2 films were grown on FeSi substrates at the heat treatment temperature of 900 degrees C from 1 min to 24 It using the molten salt technique. It is found that the films consisted of a thin surface layer and a thick underlying layer with columnar-shaped domains. The crystallographic directions of the domains are mostly randomly oriented. The beta-FeSi2 domains in the film, however, have specific crystallographic orientation relationships with the adjoining domains and the FeSi substrate. A high density of the stacking faults on the beta-FeSi2 (100) planes was also observed through the films. Moreover, the growth evolution of the beta-FeSi2 domains, the defect characteristics and the formation mechanism of the defects are discussed. (c) 2007 Elsevier B.V. All rights reserved.