[en] Gas permeability has been studied of plasma-spray-coated layers of zirconium dioxide stabilized with yttrium oxide with addition of Fe₂O₃ and Bi₂O₃ when powders have been obtained by the ordinary ceramic method and by co-precipitation of hydroxides. It has been established that gas permeability of the layers is caused by gas emission in a molecular regime. It has been shown that gas permeability of the layers depends on the method of powder preparation, regime of spraying, temperature of calcinating co-precipitated product, and the type of the additive introduced into the composition of the initial product. The lowest gas permeability of the layer is observed when the powder being sprayed is obtained by the ceramic method, has grain size 20-63 mk, and 4 mol% of Fe₂O₃ is added into the powder