The reaction mechanism of the alpha -> beta phase transformation in plutonium has been revisited using non-isothermal methods. The conditions for obtaining reproducible reaction parameters which take into account sample recovery from the effects of a previous phase transformation have been examined. The reaction mechanism for the alpha -> beta phase transformation performed on the material and under the conditions explained in this work can be described in considerably more detail than has previously been reported by following the change in activation energy as a function of the degree of transformation. This approach allows for a meaningful representation of the multi process reaction mechanism of the alpha -> beta phase transformation which reflects the change in influence of the governing mechanisms of nucleation, growth and impingement at different stages of the reaction. Crown Copyright (C) 2012 Published by Elsevier B.V. All rights reserved.