Convergent beam RHEED measurements and calculations made on MoS 2 have been extended to azimuthal rocking curve measurements on another member of the layered transition metal dichalcogenide family, NbSe 2 . These results, obtained in a dedicated RHEED apparatus at Nagoya University, show in comparison with other materials (e.g. Si, Ag) more rapidly varying structure oscillations, due to the large unit cell in the c-axis direction normal to the crystal surface. The observed structure provides the basis for polytype structure determination close to the surface.