EN
The theoretical investigation of the electron and hole spectra in a quantum dot with a linearly graded composition within the effective mass approximation is presented. The particular example is β-HgS surrounded by CdS. β-HgS core of radius r_C is surrounded by concentric spherical layers each of Hg_{1-x}Cd_{x}S composition (x is function of r) and finally, form radius r_S by CdS. The existence of these intermediate layers, as model of graded composition, influences rapidly electron and hole spectra.