The sixth industrial fluid properties simulation challenge was held in 2010. The contestants were challenged to predict mutual solubility in liquid-liquid equilibria (I,LE) for the PROGLYDE DMM (TM) + water system at various temperatures and atmospheric pressure. The temperature-dependent balance of hydrophobic and hydrophilic interactions relevant to this system is also of great scientific and practical importance as a key driving force in phenomena like self-assembly and protein folding. Because the contestants were not given the experimental benchmark data until after they had submitted their predictions, this exercise represents a relatively rare opportunity to challenge experts in the field to make predictions without a priori knowledge of the correct answer nor the option to avoid publication of their predictions if they were especially poor in comparison to experiment. Seven groups accepted the challenge and used a variety of molecular modeling and simulation methods. (C) 2011 Elsevier B.V. All rights reserved.