In this Letter, an electron beam of a transmission electron microscope was employed to activate the in situ transformation of LiOH to Li2O. It was found that the electron irradiation (200 kV) leads to a fast dissociation of large grains of LiOH into nano-structured Li2O, as nano-fibers of about 20 nm diameter and nano-particles of 30 nm. This facile transformation is attributed to the combined effect of irradiation-induced distortion of LiOH crystal structure and heating by irradiation. (c) 2006 Elsevier B.V. All rights reserved.