This paper describes a methodology to monitor axial mixing in an IsaMill as a function of mill feed flow rate, mill tip speed and media load. Steady state temperature measurements (profiles) along the mill length were used to quantify the degree of mixing during the comminution process. Combined mass and energy balances across the mill length were done to develop a predictive model for slurry mixing in the mill. The temperature measurements can be used for IsaMill control and optimisation. (C) 2014 Elsevier Ltd. All rights reserved.