The use of liposomes as drug delivery systems emerged in the last decades in view of their capacity and versatility to deliver a variety of therapeutic agents. By means of small angle neutron scattering (SANS), we performed a detailed characterisation of liposomes containing OprF, the main porin of the Pseudomonas Aeruginosa bacterium outer membrane. These OprF-liposomes are at the basis of a novel vaccine against this antibiotic resistant bacterium, which is one of the main hospital-acquired pathogens and causes each year a significant number of deaths. SANS data were analysed by a specific model we created to quantify crucial information about the structure of the liposome 1 containing OprF, including the lipid bilayer structure, the amount of protein in the lipid bilayer, the average protein localisation and the effect of the protein incorporation on the lipid bilayer. Quantification of such structural information is important to enhance the design of liposomal delivery systems for therapeutic applications.