Ozone is an important reactive gas in the troposphere,it has been frequently used to estimate atmospheric oxidation capacity.However,there are few data of surface ozone over the Arctic Ocean,especially the central Arctic Ocean.Here,surface ozone in the marine boundary layer along the cruise path during the 5th Chinese Arctic Research Expedition(June to September,2012)was investigated.1h-averaged ozone along the cruise varied from 9.4 ppbv to 124.5 ppbv with mean of 27.5 ± 11.9 ppbv.The highest mixing ratio appeared in East China Sea and the lowest in Chukchi Sea.The relatively high ozone levels over East China Sea,Sea of Japan and Sea Approaching Iceland were likely caused by transport of precursors and/or ozone from the nearby continent.Ozone mixing ratio decreased by~2 ppbv/° with increasing latitude was observed during 31 – 45 °N covering East China Sea and Sea of Japan,and during 62 – 69 °N covering Sea Approaching Iceland.Over the Arctic Ocean,ozone levels were relatively low,varying from 9.4 ppbv to 36.1 ppbv with an average of 23.8 ± 4.6 ppbv,which was not statistically different with data observed at Barrow during the same period.Unlike ozone in contaminated area,a slight increase trend of ozone in 69 – 87 °N was observed.This phenomenon may be ascribed to the role of both vertical transport and chemical processes due to solar radiation.