In this study, formations of pi-pi and CH-pi interactions in the crystallization of amorphous indomethacin (IMC) were investigated by simultaneous Raman spectroscopy and X-ray diffraction (XRD) measurements. The activation energy obtained from the change in the peak at 1616 cm(-1) corresponded to the energy obtained from the XRD diffraction peak at 21.6. We suggest that the stable IMC crystal forms by carboxyl-carboxyl interactions, which is followed by CH-pi and TC-pi interactions supporting stabilization in the indole and chlorophenyl rings. (C) 2016 Elsevier B.V. All rights reserved.