Decomposition of 1,4-dichlorobenzene (1,4-DCB) in different gas mixtures [e.g. air, N-2, 1.027%NO/N-2 (N-2 as balance gas)] in an electron beam generated plasma reactor was investigated to gain insight into the base gases influence on 1,4-DCB decomposition. Decomposition efficiency of 1,4-DCB increased with the absorbed dose increasing, the order of 1,4-DCB to be easily decomposed in different gas mixtures was: N-2 > air > 1: 027% NO/N-2, the reason for this was discussed.