Experimental study of the effect of the introduction of carbonfl uorine additives containing 14,01 – 22,72 % Al; 13 – 22,04 % F; 13,16 – 21,34 % C; 8,27 – 13,4 % Na; 0,09 – 0,14 % K; 0,66 – 1,09 % Ca; 26,11 – 42,35 % SiO2 ; 1,15 – 1,86 % FeO; 0,07 – 0,12 % MnO; 0,001 – 0,1 % MgO; 1,47 – 2,38 % S; 0,03 – 0,05 % P into oxidative fl uxes AN-348, AN-60, AN-67 when welding of steel 09G2S and aluminate-base OK Flux 10.71 fl ux at welding of steel 10HSND has been carried out. In the experiments it has been shown that from the point of view of the exclusion of formation in the weld of non-metallic inclusions, it is optimal to use carbon as a deoxidizer, as formed with the participation of gaseous carbon compounds (CO and CO2 ) are easily removed and do not contaminate the weld metal with non-metallic inclusions. The studies have shown that the carbon-fl uorine-containing additive in the composition of the fl uxes has a positive effect on the quality of the weld. It has been found out that when using the analyzed additives in the amount of 4 - 6% in the data fl uxes the overall oxygen content in the weld reduces. Fractional gas analysis revealed that the largest number of aluminates and silicates adversely affect the physico- chemical properties of welded joints, contained in the submergedarc welding of AN-60 and OK Flux 10.71, with the introduction of additives the reduction of these compounds has been observed, while in AN-348 and AN-67 fl uxes changes have been insignifi cant. When using the proposed additives the required mechanical properties, as well as impact strength at low temperatures by reducing contamination of the weld with oxide non-metallic inclusions increase, and the concentration of carbon in the weld remains at the level of the base metal.