Data are presented on the density, refractive index, viscosity, and electrical conductivity of unsaturated solutions of sodium carbonate + poly(ethylene glycol) + water at four temperatures between (293.15 and 308.15) K. The range of concentration of the solutions was from 0 to 7 mass % Na2CO3 and from 0 to 40 mass % poly(ethylene glycol) (PEG) with an average molecular weight of 2000. The experimental data on density, refractive index, and viscosity were correlated using Othmer's rule. The data on electrical conductivity were transformed to molar conductance and were correlated by group according to the percentage of PEG in each system.