The crystallization kinetics of nanocrystalline t-RuO2 in amorphous ruthenium oxide was studied by differential scanning calorimetry (DSC). It is shown that this process cannot be described by the Johnson-Mehl-Avrami model and that the two-parameter empirical Sestak-Berggren equation gives a more quantitative description. The reliability of kinetic parameters calculated from nonisothermal DSC data is tested by comparing calculated and experimental isothermal data, It is shown that a very good prediction of isothermal behavior can be obtained.