Stress evolution during Al-induced crystallization of amorphous Ge thin films was in-situ explored by multi-beam optical stress sensor (MOSS). The critical temperature at which crystallization occurs was determined by in-situ X-ray diffraction (XRD) measurement. In combination with microstructure characterization, we try to understand the mechanisms of stress generation as well as stress relaxation during metal induced crystallization (MIC). (C) 2011 Elsevier B.V. All rights reserved.