Biological membranes protect cells and are essential for their survival and damaged membranes may cause serious harm to the cell. A primary cause of damage to membranes is oxidation by radicals present in the body. The lipids which comprise the membrane are changed by oxidation and as a result so is the membrane structure. Insight into how lipid oxidation relates to structural changes in the membrane is an essential step to understand how membrane oxidation is related to diseases. By creating mixed bilayers of a phospholipid and varying amounts of an oxidised lipid and determining the structure with neutron reflectivity, we aim to understand how the structure of the bilayer is changed when oxidised lipids are introduced to the bilayer.