The evolution of chord length distributions of crystals during the isothermal crystallisation and post-crystallisation remelting of palm oil was monitored in a stirred, jacketed glass vessel using the Focused Beam Reflectance Measurement (FBRM) instrument probe at isothermal temperatures between 24 and 32 degrees C. Results show that the mean crystal chord length increases with increasing isothermal temperature up to 26 degrees C but then decreases again at higher temperatures. This appears to be due to the greater susceptibility for crystals formed at higher temperatures to break up into smaller fragments. An induction time is clearly evident in all experiments and this increases with temperature as expected. Post-crystallisation remelting experiments showed evidence of deagglomeration and disintegration of solid entities. This is thought to be due to the melting of bridges that hold crystals together in agglomerates. This is one of the first studies to demonstrate that the FBRM technique is an efficient in situ monitoring tool, capable of providing valuable information regarding the dynamic evolution of particle population and size as well as the detection of events related to crystallisation and melting of palm oil. (C) 2011 Elsevier B.V. All rights reserved.