Lithium oxide was selected as an emission spectroscopic marker in yttria stabilized zirconia (YSZ) thermal barrier coatings (TBCs). The spectral response of excited lithium atoms from dip-coated YSZ containing 5, 3, 1, and 0.3 wt.% lithium oxide and plasma-sprayed YSZ containing I wt% lithium oxide was examined under an oxy-acetylene flame. Results showed that the intensity of lithium emission spectrum is a function of the concentration of lithium oxide in the YSZ, the flame temperature, and the degree of TBC degradation. It indicates that an emission spectroscopy can be used to monitor the degradation of TBCs.