In order to apply the concept of the dissipation function during the first-order phase transition (FOPT) in solids, we measured the internal friction Q-1 and shear modulus μ for a range of frequencies of polycrystalline ceramics VO2 as the sample passed through a FOPT across the temperature range of 300-0420K. The experiment was repeated for different temperature variation rate T. We have found that for each frequency, a maximum of Q-1 and a minimum of μ occurred at the same temperature Tp when T was kept constant. The numerical values of the dissipation function AGR plus other FOPT parameters have been deduced using Q-1 data. The general trend of AGR-T and other results are found to be consistent with known physical aspects.