EN
We studied the luminescence of bulk Zn_{1-x}Cd_{x}Se solid solutions, epitaxial ZnSe films and ZnSe_{1-x}S_{x}/ZnSe_{1-y}S_{y} superlattices at T=2-80 K. The analysis of the bands of exciton radiative annihilation with simultaneous emission of 1 or 2 LO phonons shows that the excitons in the studied samples can be considered as free particles with thermalized distribution of kinetic energies. In ZnSe_{1-x}S_{x}/ZnSe_{1-y}S_{y} superlattices a three-dimensional character of exciton motion was established. The periodic potential of superlattice perturbs the exciton wave vector and induces additional elastic scattering of excitons.