Abstract: The dielectric spectra of doped cubic silver bromide emulsions are studied.1-8 mol% Cd(NO₃)₂, CdCl₂, CdBr,, Cu(NO₃)₂, CuCl₂, CuBr₂, KCl and KBr are added into the cubic AgBr emulsions, respectively.It is observed that the peaks of dielectric loss curves are broadened and markedly shifted to lower frequencies in silver bromide emulsions with CdCl₂, and CdBr₂, while there is no change in dielectric spectra in the case of Cd(NFO₃)₂ and Cu(NO₃)₂ doping.For emulsion samples with CuCl₂, CuBr₂, KCl and KBr, the peaks of dielectric loss curves are shifted slightly to higher frequencies.On the basis of these experimental results, it is deduced that Cd⁺⁺ ions can incorporate into the crystal lattice on the surface of silver bromide crystal only in the presence of excess halogen ions in the emulsion, and that it is difficult for Cu⁺⁺ ions to incorporate into the crystal lattice even when excess halogen ions are present.The difference in the behaviour of Cd⁺⁺ and Cu⁺⁺ ions is attributed to the difference between the radii of both ions, the electron configuration of the ions and their coordination in the crystals.Finally, the condition under which the Sillars equation applies to a photographic emulsion system is considered.