The aqueous sodium sulfide solution has been used for pre-epitaxial preparation of epi-ready InSb (0 0 1) substrates for molecular beam epitaxy (MBE) of InSb layers. X-ray photoemission spectroscopy study shows that the S-treated surface of InSb (0 0 1) substrate generally does not contain a native oxide layer and is covered with a sulfide protecting overlayer. Atomic-force microscopy and transmission electron microscopy have been applied to compare surface topography and structural properties of InSb layers grown by MBE on S-treated and untreated epi-ready InSb (0 0 1) substrates. The MBE growth of InSb layers with very smooth surface possessing the root-mean-square roughness as low as 0.1 nm and good structural quality has been demonstrated on the S-treated substrates. (C) 2015 Published by Elsevier B.V.