Caking in sucrose is a major problem for the sugar industry, especially during transportation. Liquid bridging in sucrose is the first step towards caking. This paper demonstrates, by measuring the strength of the liquid bridges and then the strength of the subsequently formed solid bridges under different water activity conditions that the critical water activity for initiation of caking is about 0.8. The identification of this point allows the conditions under which bulk sucrose is stored and transported to be specified to prevent the occurrence of water activities going above this critical level to eliminate caking. (c) 2005 Elsevier Ltd. All rights reserved.