The ground state structures and several isomers of osmium clusters of up to 14 atoms were obtained from the basin-hopping algorithm within a density functional theory. The small Os clusters favor cubic-based configurations which are similar to those found in Ru clusters. In contrast, Os clusters show much higher binding energy and stability than Ru clusters, which suggests that Os clusters have the potential to be better catalysts than Ru clusters. Magnetic property of small Os clusters also studied. These results provide an elementary understanding of small osmium clusters and provide a catalyst alternative to other group VIII clusters. (C) 2012 Elsevier B.V. All rights reserved.