We present a detailed study of the (001) surface of the Al 9Co2 crystal using both experimental methods and first-principles calculations based on the density functional theory. Experimentally, the (1 × 1) low-energy electron diffraction pattern combined with the composition determined using X-ray photoemission spectroscopy is consistent with a bulk terminated surface. In addition, scanning tunneling microscopy (STM) measurements highlights the presence of only one type of surface termination. Combining experimental results with electronic structure calculations provides many arguments to correlate the observed surface termination with the dense pure aluminum layer present in the Al 9Co2 bulk structure: (i) calculations show that this termination presents a lower surface energy compared to another conceivable termination obtained also from bulk truncation, (ii) step height measurements are consistent with calculated interlayer spacings, (iii) calculated broadened densities of states and simulated STM images are qualitatively in agreement with the experimental photoelectron spectra and the experimental STM images. © 2011 American Chemical Society.