High-frequency electrodeless light sources are known as bright radiators with the line spectrum, characterized by high intensities and narrow line shapes. The lamp balloons are mostly made of quartz and filled with a metal and buffer gas. These light sources must be optimized for each application in accordance with the specific requirements of radiation quality, lifetime, and stability. This work is devoted to the diagnostic of high-frequency electrodeless light sources for their use in high precision atomic absorption analyzers and other applications like disinfection. The spectral line intensities and profiles were studied in discharges with arsenic and thallium fillings. Special attention is devoted to the UV lines of 193.7 nm and 197.2 nm of As and 377.6 nm of Tl spectral lines. The intensities and profiles were measured by means of a Fourier transform spectrometer. The deconvolution procedure was implemented to obtain the real form of emitted profiles for further analysis. The integrated areas, values of self-absorption, and other parameters were obtained and compared for both fillings as a function of working regimes.