on anarm´ onica. Descriptores: Semiconductor; TlGaS2; temperatura. The isobaric temperature dependence of the Raman active phonons of layer TlGaS2 compound was studied in the temperature range from 26 K to 300 K, approximately. The results showed that for the internal modes of material the anharmonic contributions to the phonon decay is higher than the corresponding contribution of the external modes. Moreover, the temperature variation of the external mode frequencies temperature variation is more affected for the volume changes of the material than for the anharmonic participation.