During heat treatment of Ni-based superalloys, the rate of change of gamma prime phase particle sizes and volume fractions affect the final grain size and thus the material's mechanical properties. Experimental measurement of the supersolvus dissolution kinetics is difficult due to rapidly changing volume fractions at the heat treatment temperatures. By incorporating a heat transfer analysis, a method of extracting the kinetic constants from experimental observations is presented. The results are in good agreement with phase field simulation predictions.