Corn seed were treated with pure oxygen and oxygen charge with ozone during 6.8 or 20.5 min. Germination tests were started immediately or 48h after treatment. Effects of oxidative treatments on germination were determinate by measuring seedlings and roots (>3mm and >20mm) rate at 3,4 and 5 days after imbibition. Results obtained for treated seeds samples were higher than untreated one. A faster start of germination for treated samples than untreated was observed. This early germination start led to have more germinated seeds with large root in treated samples than untreated at 4 and 5 days. Never the less a too long ozone treatment seemed to be penalizing on germination rate whereas a short one seemed to be most beneficial.