The kinetics of gold-induced crystallization (AuIC) of amorphous silicon suboxide (a-SiOx, x = 0.2) films in the layer exchange mode was detailed studied by variation of the annealing temperature in the range of 220–250 °C for the first time. In situ optical microscopy performed during annealing made it possible to study the processes of the nucleation and the growth of Si crystal structures. A decrease in the nucleation rate during annealing was shown, which is probably associated with coarsening of grains in the Au film which is confirmed by scanning electron microscopy. Obtained experimental data along with the simulations carried out within the framework of the Kolmogorov–Johnson–Mehl–Avrami (KJMA) theory made it possible for the first time to obtain the values of the activation energies for the nucleation, the growth, as well as the overall process of AuIC of a-SiO0.2 which amounted to 2.51 ± 0.80, 0.31 ± 0.10, and 1.62 ± 0.15 eV, respectively.