Pulse-modulated high-power inductively coupled plasma (PM-ICP) as a radical source of high flux density was utilized to improve the UV emission efficiency of ZnO. The irradiation of argon-hydrogen PM-ICP plasma gave the improvement of the UV emission at 380 nm. The relationship between the treatment condition and the emission properties was examined with respect to hydrogen dissolution. When treated in the tail plasma flame with adequate cooling, the specimen showed the intense UV emission. The control of heat flux by mixing nitrogen gas to the hydrogen-containing plasma also had a favorable influence on the UV emission. (c) 2005 Elsevier B.V. All rights reserved.