Аннотация:The expected X-ray emission of the cavities formed by stellar wind is calculated within the framework of the model of Weaver et al. (1977). Calculated results are presented for eight ring nebulae around WR and O(f) stars. Observations of them in the X-ray range will permit a test of whether a layer of hot wind exists in the cavities or whether the wind leaks out rapidly through irregularities in the structure of the shell. It is shown that observations of the ring nebulae NGC 6888 and Sh 119 are the most promising; their expected emission spectra in the 0.1-4 keV range are presented.