Abstract: This paper described a metal converter in which vitreous carbon is employed as support. When NO₂ has a concentration of 1.058-6.372mg/m³, it could be quantitatively converted into NO at a space velocity of 40000hr^-1 and under 100℃. Both rate of conversion and recovery are 100%. In the course of seven days' continuous and forty days' contiual operation, it shows no change in main characteristics and is free from NH₃ interence.