The progressive decay in the CO2 carrying capacity of limestone is one of the major limitations of the CaCO3-CaO thermochemical cycle (Ca looping) which forms the basis of a number of emerging energy conversion technologies. A reactivation method consisting of hydrating and dehydrating the spent lime was reported to restore its CO2 carrying capacity but also to considerably increase sorbent friability thus limiting the applicability of this method in an industrial setting. However there is little experimental information about the mechanism of this friability increase. This work aimed at collecting experimental data on the evolution of sorbent friability and the dominant attrition mechanisms during and after reactivation. The dehydration step was identified as the point at which the weakness of the sorbent was first detected. This weakness manifested as an increased tendency for fragmentation by chipping of the dehydrated sorbent and all sorbents deriving from it. A hypothesis was postulated to explain the results. (C) 2013 Elsevier Ltd. All rights reserved.