Sugarcane juice (JCP) and whey protein concentrate (WPC) are products of great interest due to their contributions of carbohydrates and proteins, respectively, and they have the ability to be transformed into powdered products. In this work, the influence of spray drying conditions on the processing performance and physicochemical properties of the JCP and WPC combined system were evaluated through applying a response surface methodology by central composite design. The independent variables were as follows: inlet air temperature (130-180 degrees C), outlet air temperature (75-90 degrees C), atomizer disk speed (21,000-26,000 rpm) and WPC contribution in the feed (40-90% d.b.). The results indicated that the drying process conditions had a significant statistical effect (p < 0.05) on the effective yield, adhesion of solids to the dryer walls, moisture content, water activity, solubility, bulk density, particle size and morphology. Finally, the optimization process showed that the best operating conditions for spray drying of the JCP and WPC combined system were an inlet temperature of 130 degrees C, an outlet temperature of 88 degrees C, an atomizer disk speed of 21,000 rpm and 78.83% w/w of WPC solids, with an effective yield of 80.13 +/- 0.82%, powder moisture content of 4.3% (w.b.), water activity of 0.2014, solubility of 91.62% and bulk density of 0.44 g/ml. Moreover, the wettability, hygroscopicity, glass transition temperature and color of the powder were analyzed. (C) 2017 Elsevier B.V. All rights reserved.