In this work, the isothermal gas-liquid equilibrium (GLE) data were measured for the system of polyethylene glycol 400 (PEG 400) + N,N-dimethylformamide (DMF) + SO2 + N-2 at 308.15 K and 123 kPa with SO2 partial pressures in the range of (16.8 to 115) Pa. The Henry's law constant (H') and standard Gibbs free energy change (Delta G) were calculated from these GLE data. Furthermore, the densities and viscosities of binary mixtures of DMF + PEG 400 were also measured over the whole concentration range at T = (298.15 to 313.15) K. From the experimental data, including density and viscosity values, the excess molar volumes (V-m(E)), and viscosity deviations (Delta eta), the calculated results are fitted to a Redlich-Kister equation to obtain the coefficients and estimate the standard deviations between the experimental and the calculated quantities.