This study presents interfacial tension and viscosity experimental data, at 30 degrees C, for aqueous two-phase systems (ATPS) composed of poly( ethylene glycol) ( PEG) with different molar mass ( 4000, 6000, and 8000) g . mol(-1) and maltodextrin (MD), with molar mass of 2800 g . mol(-1). Interfacial tension and viscosity were measured by using a spinning drop tensiometer and a rolling ball viscosimeter, respectively. An increase on the PEG molar mass resulted in an increase of interfacial tension and viscosity. The interfacial tension varied from (0.038 to 0.121) mN . m(-1) for the systems formed by PEG 4000 (w = 0.08) + MD (w = 0.35) + water ( w = 0.57) and PEG 8000 ( w = 0.10) + MD ( w = 0.30) + water ( w = 0.60), respectively. Viscosity values varied from (7.9 x 10(-3) to 2.17 x 10(-2)) Pa . s for the PEG-rich phase and from (4.51 x 10(-2) to 6.54 x 10(-2)) Pa, s for the MD-rich phase.