The sound velocity measurements provide valuable information about the physical properties and molecular interactions of the liquids.The apparent molar isentropic compressibility of homologous dicarboxylic acids(oxalic,malonic,succinic, glutraric and adipic acids)have been determined in water +acetone,water + methanol mixtures.The sound velocity increases as the acetone and methanol contents in water increase and passes through a minimum.In other words, the isentropic compressibility decreases and passes through a minimum in the same region. The decrease in isentropic compressibility may be due to the fact that the organic solvent leads to a particular break down of water rendering it less structured than in pure water.Conductance data in different temperature and concentration ranges are of great importance in order to understand the ionic transport processes in aqueous and mixed solvents.