The complex ClBrO has been generated in argon matrix by photolysis of the O-3:BrCl complex and has been characterized by its Fourier-transform IR spectrum. Wavelength dependence of ClBrO photochemistry has been determined in the range from 317 to 870 nm by using laser irradiations and in the frequency region of a Nernst globar. Visible irradiation between 633 and 700 nm transforms ClBrO into BrClO and that above 700 nm continues the transformation into BrOCl. Reverse photoisomerization of BrOCl into ClBrO or BrClO was not observed. BrClO but not ClBrO is sensitive to IR irradiation. Calculations are combined with experimental observations to present a model for the photochemical isomerization of ClBrO and a comparison with related Cl2O and Br2O isomerizations.