In this work, physical properties such as dynamic viscosity at (298.15 to 338.15) K, surface tension, and refractive index at temperatures (303.15 to 333.15) K of pure and aqueous N-methyldiethanolamine (MDEA) solutions (with mass fraction of MDEA of 0.3228 and 0.4880) were measured at atmospheric pressure and correlated. A thermogravimetric analyzer (TGA) was used to study the thermal stability of solvents in the presence of nitrogen (20 mL·min -1), at a heating rate of 10°C·min-1. © 2008 American Chemical Society.