Drying kinetics data are of paramount importance for simulating industrial spray drying operations. This study reports for the first time the drying kinetics of skim milk droplets with 50 wt.% initial solids, as typically encountered in practice. The changes in droplet temperature, moisture content, and diameter were experimentally determined using glass-filament single droplet drying technique. Enhanced effects of drying temperature on droplet shrinkage were observed. Experimental data were correlated using the Reaction Engineering Approach (REA) with the master activation-energy curve providing a good description to the drying histories. Activation energy curves obtained here were compared with previous data from lower initial concentrations, as well as the plot obtained using a preliminary desorption method. The outcomes support the suitability of REA to interpret the drying behavior of skim milk with high initial solids level, which is the norm for practical spray drying of milk with feed concentration of around 50 wt.%. (C) 2011 Elsevier Ltd. All rights reserved.