A novel neutron and X-ray reflectometry sample environment is presented for the study of surface-active molecules at solid-liquid interfaces under shear. Neutron reflectometry was successfully used to characterise the iron oxide-dodecane interface at a shear rate of [Formula: see text] [Formula: see text] using a combination of conventional reflectometry theory coupled with the summation of reflected intensities to describe reflectivity from thicker films. Additionally, the structure adopted by glycerol monooleate (GMO), an Organic Friction Modifier, when adsorbed at the iron oxide-dodecane interface at a shear rate of [Formula: see text] [Formula: see text] was studied. It was found that GMO forms a surface layer that appears unaltered by the effect of shear, where the thickness of the GMO layer was found to be [Formula: see text] Å under direct shear at [Formula: see text] [Formula: see text] and [Formula: see text] Å when not directly under shear. Finally, a model to analyse X-ray reflectometry data collected with the sample environment is also described and applied to data collected at [Formula: see text] [Formula: see text].