Undesired particulate agglomeration can create powder flow issues during manufacturing. Potassium chloride (KCl), a commercial product used in powder form as a potassium source, is known to agglomerate. The main objective is to develop a method to assess KCl agglomeration, then use it to understand its driving forces and the phenomena taking place. Based on industrial data in pharmaceutical manufacturing, the following 5 parameters are considered as critical in terms of agglomeration: conditioning humidity, conditioning time, drying, applied pressure and particle size. Beakers containing 40 g of original or ground KCl powder are compacted under specific humidity conditions in a bell jar. Once the beakers are conditioned, agglomerate hardness tests evaluate agglomeration extent by correlating it with the energy required for powder penetration. This energy is calculated from force-distance curves. The results show that the Area Under the force vs distance Curve (AUC) is a good indicator of agglomeration extent. Thus, the AUC is a scalar and has units of work. Based on AUC analysis, the highest agglomeration is found in conditioning humidity of 85% relative humidity (RH), original particle size, drying and conditioning time of 16 h. The agglomeration of original versus ground particle size powders is further investigated over time in a conditioning test. Preliminary tests validate our method and indicate that KCl premixing with other materials can solve agglomeration problems encountered during manufacturing processes as KCl-particle-particle interactions per unit volume are reduced. (C) 2018 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.