Photodissociation kinetics of iron–boron (FeB) pairs in boron‐doped Czochralski silicon is studied experimentally using different light sources. It is shown that the FeB dissociation rate depends not only on integrated light intensity and overall carrier generation rate, but also on spectral composition of illumination. The value of the material constant of dissociation K varies and has been determined to be within s. The investigation reveals an increase in the dissociation rate with increase in photon energy. The results indicate that recombination‐enhanced defect reaction is the primary factor in the second stage of pair dissociation.