Oxidation of membrane lipids by Reactive Oxygen Species, ROS, in cells may impact ageing, cell apoptosis and cancer. We propose to use our skills obtained studying the oxidation of fatty acids and lipids at the air-water interface to investigate the attack by aqueous singlet oxygen, a member of the ROS family, on a lipid bilayer supported at the solid-water interface. The bilayer will be composed of different isotopologues of DPPC (varying deuteration schemes to label different parts of the lipid) on a quartz window in a flow cell and exposed to varying levels of singlet oxygen. Neutron reflection will allow us (1) to record the kinetic decay of head only, tail only and complete lipid by selective labelling and (2) investigate the change in structure (film thickness and integrity) of the oxidized lipid bilayer kinetically. The work is proof of concept.