A new method to measure the solubility of solids and the corresponding saturation density is presented in this work. The apparatus is based on the static-synthetic method. The main parts of the apparatus are a vibrating tube densitometer and a sapphire tube cell. Most important advantage of this method is: compressed densities of a supercritical fluid (containing a dissolved solid) are obtained far and close to the solid solubility limits without any sampling and expensive analysis equipments. The variable volume cell is used to determine the solid solubility limit while the vibrating tube densitometer (VTD) gives numerous density data of the compressed phase, in a very fast way, on a large range of pressures and temperatures. The testing of the apparatus and procedure were made by the measurement of the solubility of naphthalene in supercritical CO2. Solubility and saturation density data were compared with literature data. A method to check the self-consistency of experimental data was used in order to validate our experimental solubility results. The experimental data reported here are in good agreement with those published in the literature. (c) 2005 Elsevier B.V. All rights reserved.