High-quality single crystals of the heavy fermion superconductors CeCoIn5 and CeIrIn5 have been studied by means of low-temperature scanning tunneling microscopy. Methods were established to facilitate in situ sample cleaving. Spectroscopy in CeCoIn5 reveals a gap which persists to above Tc, possibly evidencing a precursor state to superconductivity. Atomically resolved topographs show a rearrangement of the atoms at the crystal surface. This modification at the surface might influence the surface properties as detected by tunneling spectroscopy. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.