The partial specific volume of a macromolecule in a solution may be thought as the increase in the volume of an infinte amount of solution when one gram of component 2 (polymer) is added. The partial specific volume and thermal expansion in solution are two important properties in polymer characterizations. Both of the above quantities in solution depende on polymer-solvent and polymer – polymer interactions which provides information about state and conformation of polymer in solution. Experimentally, it has been established that these interactions depend on temperature, solvent, polymer and polymer concentration. Partial specific volume depends on molecular mass of a polymer too; however, if the molecular mass is above 100 000 the dependnce is not so notable. In this study a DMA 5000 Anton Paar densitometer was used to measure the density of polymer solutions from 15 °C to 30 °C. The results show that the partial specific volume of poly(3,5-dimethyphenylacrylate) is temperature dependet, it increases as the temperature increases, is considerably bigger than poly(methyacrylat).