Carbon monoxide is a common environmental pollutant. The maximum permissible concentration of carbon monoxide (MACCO) in the working area is 20 mg/m3, which is dangerous for the environment and humans. Various catalysts are used to reduce its concentration in the air. Topical issues are the development of catalysts for low-temperature oxidation of CO (KNO-CO) for personal respiratory protection equipment. Catalysts for respiratory purposes should ensure stable air purification to a CO concentration below or equal to the MACS at ambient temperature and high humidity of the gas-air mixture (GAM). An analysis of studies in the field of the development of KNO-CO showed that Wacker-type metal-complex catalysts supported on various carriers containing palladium(II), copper(II) salts and other additives in their composition are promising. A feature of such catalysts is the ability to vary their activity by changing the nature of the support. The natural mineral phlogopite (N-Phl) was first used as a support for palladium-copper complexes catalyzing the low-temperature oxidation of carbon monoxide with atmospheric oxygen. To change the physicochemical properties of phlogopite, the acid leaching method was applied. For these purposes, the original samples were treated by the reflux method for 1 hour with nitric acid of various concentrations. As a result, a series of samples Х̅Н-Phl-1was obtained, where Х̅ = 0.25; 0.5; 1.0; 3.0; 4.0; 6.0 and 8.0 mol/l, which were used to obtain catalytic compositions of the composition K2PdCl4-Cu(NO3)2-KBr/Х̅H-Phl-1. It was identified by the Rietveld method that natural phlogopite is crystalline and polyphase in composition. The content of phlogopite in the original sample is 62.7 wt. %. Along with the phlogopite phase, the mineral contains diopside phases; vermiculite; some other phases, for example, clinochlore, cordierite, etc. Phlogopite changes its structural and physico-chemical properties as a result of physical and chemical impact. Our studies have shown that when exposed to 0.5; 1.0; 3.0; 6.0 mol/l nitric acid, no noticeable changes in the structure of phlogopite are observed. Scanning electron microscopy (SEM) showed that phlogopite has a typical lamellar morphology. Individual lamellas (strips) have a smooth surface without obvious pores. Under the action of nitric acid, the structure of phlogopite undergoes changes. Thus, in the case of the 3H-Phl-1 sample, the lamellar morphology is preserved, but separate destroyed deformed layers with uneven edges appear, the surface of which is wrinkled and covered with depressions. In the case of 6H-Phl-1, the delamination is enhanced, cavities of different sizes are formed between the strips; the edges are uneven. When applying salts of Pd(II) and Cu(II) on the acid-modified form of 6H-Phl-1, the separation is enhanced; the lamellae are partially destroyed, the surface is not smooth, wrinkled.The kinetics of oxidation of carbon monoxide by air oxygen in the presence of compositions K2PdCl4-Cu(NO3)2-KBr/Х̅Н-Phl-1 are presented in fig. 1 and summarized in table. 1. It should be noted that samples based on untreated phlogopite, as well as those modified with nitric acid (0.25, 0.5, 1.0 mol/l) did not show catalytic properties at the outlet of the СCOf= СCOin (Table 1). The kinetic data reflect the change in the final concentration of CO over time during the oxidation of carbon monoxide with atmospheric oxygen in the presence of catalysts in which acid-modified forms of phlogopite Х̅H-Phl-1 act as carriers, where Х̅ = 3.0; 4.0; 6.0 and 8.0 M HNO3 Table 1 Influence of the effective contact time of the gas-air mixture with the catalyst and the pH of the suspension on the degree of CO conversion in the presence of catalysts K2PdCl4-Cu(NO3)2-KBr/Х̅Н-Phl-1 Conditions: CPd(II) = 2.7210-5; CCu(II) = 5.910-5; CKBr = 1.0210-4 mol/g; = 300 mg/m3; U = 4.2 cm/s t = 20 С. Carrier h, cm ef, s рНs W109, mol/(gs) CCOf, mg/m3 st, % Win Wst after 1 min stationary mode N-Phl 2,0 0,48 6,66 300 300 0 0,25H-Phl-1 2,1 0,50 6,09 300 300 0 0,5H -Phl-1 2,1 0,50 6,05 300 300 0 1H -Phl-1 2,2 0,52 6,01 300 300 0 3Н-Phl-1 2,2 0,52 5,72 14,82 9,60 53 140 53 4H-Phl-1 2,3 0,55 5,69 17,40 14,40 10 60 80 6H -Phl-1 3,2 0,76 5,63 17,70 16,44 5 26 91 8H -Phl-1 3,3 0,79 5,57 17,64 17,10 6 15 95 So, for the first time, natural phlogopite (N-Phl), an aluminosilicate from the group of mica with a layered structure of 2:1, is used as a carrier for palladium-copper complexes that catalyze the low-temperature oxidation of carbon monoxide with atmospheric oxygen. Studies have shown that Pd(II) and Cu(II) compounds applied by impregnation to the surface of natural phlogopite do not exhibit catalytic activity in the oxidation of carbon monoxide with oxygen. To change the structural, morphological and acidic properties of phlogopite, the acid leaching method was applied. Carriers and catalysts were characterized by XRD, SEM; for the samples of the initial and acid-modified phlogopite, the pH values of the suspensions were determined under equilibrium conditions. It wasfound that the oxidation of CO with oxygen with the establishment of a stationary mode is carried out in the presence of catalysts K2PdCl4-Cu(NO3)2-KBr/Х̅Н-Phl-1, when Х̅ ≥ 3 mol/L, however, the condition when the concentration of CO at the outlet of the reactor is less than the maximum permissible concentration, observed only at Х̅= 8.0 mol/L. This sample corresponds to the highest degree of amorphization and formation of nanosilicon (XRD), the greatest increase in volume due to phlogopite layering (SEM), and the lowest pH value of the suspension. A catalyst has been obtained that is promising for use in respiratory devices.