The authors have proposed a way for producing hydrogen fluoride (the major fluorinating agent in the modern industry) from ammonium bifluoride (by-product in the production of extraction phosphoric acid, tantalum, niobium, etc.) by burning up NH4F∙HF in oxygen. Calculations performed via program complex ASTRA.4 showed that the only fluorine-containing substance was hydrogen fluoride, whereas nitric fluorides and oxyfluorides being absent under the ratio of chemical elements N-1.0; H-5.0; F-2.0; O-1.5 (according to the proposed process), in the temperature range 600 – 2500 K, in thermodynamically equilibrium mixture. The combustion of ammonia in oxygen in the presence of hydrogen fluoride was experimentally investigated and it was found the feasibility of forming a stable flame, where a molar ratio of ammonia/hydrogen fluoride consumptions was 1: 2, only by using methane as a fuel. The conditions for the ratio of component consumptions were determined.