The density and surface tension of 0.12 to 0.75 acid mass fraction in aqueous sulfuric acid solutions have been measured in the temperature region from (220 to 300) K. The density has been expressed as a polynomial of the acid mass fraction and temperature, fitting the new measurements together with the tabulated values from international Critical Tables (1928). Older literature data for the surface tension of aqueous sulfuric acid has been corrected for systematic errors and used with the new data to derive a parametrization of the surface tension as a function of acid mass fraction and temperature.