A fluidic cell based setup is described which allows for microbeam grazing incidence small angle x-ray scattering characterization of the interface between a solid substrate and a flowing liquid. This cell can potentially be used to study in situ a wide variety of systems ranging from synthetic and natural colloids to biological molecules. The selected channel geometry enables the characterization of the solid-liquid interface during mixing of different solutions. As a proof of concept, measurements on an aqueous gold nanoparticle solution in contact with a glass surface are presented that show that the structure at the interface can be probed during flow.