Chemical reactive fields of non-thermal plasma flowing were clarified by using both experimental and numerical methods in the present study. The plasma was generated by using needle-plate electrodes with applied voltage of 12 kV and a square wave of 20 Hz. The operating gas was air injected at a rate of 1-10 SI/min through a rectangular reactor with a 3 x 7 mm cross section. Distributions of gas velocity, gas temperature and NO concentration were clarified by experimental and numerical methods. The NO concentration was strongly influenced by the gas flow rate, because the N concentration was rapidly decreased in the case of small gas flow rate. (C) 2003 Elsevier B.V. All rights reserved.