The top layer of a cleaved surface of the single layered manganite La0.5Sr1.5MnO4 is measured with crystal truncation rod scattering. Knowledge of the surface structure of strongly correlated electron systems is needed for nano-science and device application of such systems. The result shows that the cleaved surface is terminated by La/Sr layer and has little surface roughness. (c) 2006 Elsevier B.V. All rights reserved.