A technique for synthesis of high-pure tellurium oxide (IV) by chemical combustion of tellurium vapor in dry oxygen has been developed. The technique allows synthesizing crystalline β-TeO2 (paratellurite) free of OH-groups. Numerical simulation of the technique processing in a quartz-glass reactor let’s propose the mechanism of crystalline TeO2 formation as 2–5 μm particles and found out ranges of parameters of the combustion reaction of Te-vapor in oxygen atmosphere: temperature, tellurium vapor pressure, argon-carriage-gas flow, oxygen flow and total gas pressure in the reactor. The experimentally optimized parameters made it possible to synthesize crystalline β-TeO2 as pure as 99.999994 wt% (65 elements detected) using 99.997 wt% Te and 99.999 vol% oxygen with the yield of 85%. •Numerical simulation of the combustion reaction of Te vapor in oxygen was fulfilled.•Synthesis technique of crystalline TeO2 by the chemical combustion reaction was developed.•β-TeO2 powder preparation with chemical purity 99.999994 wt% was produced.