A photochemical process is proposed as a new efficient N(2)O removal technique in N(2) or air at atmospheric pressure and room temperature without using any catalysts. N(2)O diluted in N(2) or air was decomposed into N(2), O(2), and NO by using a 193 nm ArF excimer laser. The maximum conversion of N(2)O in N(2)O/N(2) or N(2)O/N(2)/O(2) mixtures was 93% at a laser power of 136 mJ, a repetition frequency of 5 Hz, and an irradiation time of 30 min. The formation ratios of N(2):O(2):NO in N(2)O/N(2) and N(2)O/N(2)/O(2) mixtures were 64:31:5.1% and 60:27:13%, respectively. The decomposition mechanism of N(2)O under 193 nm photolysis was discussed by comparing experimental data with calculated model using known photochemical and gas kinetic data.