We present the results of experimental investigations on dielectric properties of ZnSe1-xTex epilayers by capacitance and dissipation factor at temperature 5 K<T<475 K and frequency 20 Hz<f<1 MHz. A Debye-like relaxation of dielectric behavior has been observed, which is found to be a thermally activated process. The activation energies obtained from capacitance and dissipation factor are in very good agreement. The activation energies decrease with the increase of Se content, and range from 662 to 819 meV. The results are described by means of the four-center model, in which the number of different atoms occupying the nearest-neighbor sites of defects results in a different activation energy.