In this paper systematic density measurements of gelatin/water and K-carrageenadwater gels are presented in a wide range of concentrations and temperatures. From about 600 measurements for gelatidwater and about 500 measurements for the system K-carrageenadwater empirical relations for both systems have been derived which allow to calculate the densities of these gels in a limited concentration range if the temperatures and the polymer weight fractions are known. The calculated densities have an accuracy of better than 0,001 g/cm -3 compared with the directly measured densities. If the extrapolated partial specific volumes of the pure polymer are plotted against the temperature, a jump with an inflexion point can be detected at about 23-24°C for both systems. These data indicate a A-type transition of the expansion coefficient a for both systems at 23-24°C although there are still too few data to make clear conclusions.