Recombination radiation carries definite information on the parameters of semiconductors, which enables the use of luminescence, excited by light (photoluminescence) or an electron beam (cathodoluminescence) for monitoring the parameters of semiconducting graded-gap structures. In this work the authors develop a theory which can be used in the practice of photo- and cathodoluminescence measurements of the parameters of graded-gap semiconducting structures. The recombination radiation used is assumed to be isotropic. The practical method of luminescence analysis are based on the analysis of spectrometric measurements in accordance with the theory of transfer of the primary excitation through the bulk of the crystal as a result of diffusion and drift of non-equilibrium charge carriers (NCC) in the quasielectric field in the graded-gap layer.