Blood coagulation is a crucially important physiological process. At the molecular level, it is a sequential cascade of proteolytic reactions. The product of each step catalyzes the following step, culminating in the cleavage of fibrin to fibrinogen which ultimately forms the clot. The steps of the cascade are catalyzed by clotting factors. In this study, we focus on one of the key factors in the cascade, factor VIII (FVIII). It performs its function in complex with a phospholipid, phosphatidyl serine (PS), at the surface of the activated platelets, however, the structure of the membrane-bound form of the factor remains unknown. The focus of our study is to investigate by neutron reflectometry FVIII bound to PS-containing supported lipid bilayers and to study redistribution of lipids that is caused by its binding to SLBs.