We report herein recent advances made by our group and others in the field of oxygen-centered radicals generated under photocatalysis. Thanks to the design of new O-radical precursors, these radicals can now be efficiently trapped by unsaturated systems in an intermolecular manner, via the formation of a new C-O bond. 1 Introduction 2 Reactions Involving Carbonyloxy Radicals 3 Reactions Involving Fluoroalkoxy Radicals 4 Reactions Involving Alkoxy Radicals 5 Conclusion.