A synthesized version of the dioxygen chemistry is reviewed. Since superoxide, hydrogen peroxide and hydroxyl radicals are products of the dioxygen reduction, a Chemical characterization is advanced. In addition, Fe, Mn and Cu integrated in enzymes cormected with reduction products of oxygen in plants aie chemically characterized. An overview of the oxygen metaboiism in photosynthesis follows. Accordingly, the production of triplet oxygen through the water-splitting complex as well as the production and control of singlet oxygen and hydrogen peroxide in the photosystem 2 are evaluated. Furthermore, the superoxide and hydrogen peroxide production and control in photosystem 1 are evaluated. The chloroplast oxy-radicals production under stress conditions, mainly an interaction between zeaxanthin and singlet oxygen under photoinhibitory conditions, as well as the interactions between sulphin dioxide and superoxide are given. Furthermore, the effects of low temperatmes on the oxygen metaboiism as well as the nutritional effects of Mn, Fe and Cu on the oxy-radicals production and control are evaluated.