Densities, speeds of sound, and refractive indices of the binary nonane + triethylene glycol dimethyl ether (2,5,8, 1 1-tetraoxadodecane or triglyme or TODD) have been measured at the temperatures 288.15 K, 293.15 K, 298.15 K, and 308.15 K and atmospheric pressure, over the entire composition range. Using these data, excess molar volumes and increments in speed of sound and refractive index have been calculated. Excess quantities and increments have been fitted to a variable-degree polynomial equation. The correlation parameters together with the standard deviations between the experimental and calculated values were derived.