Interfacial reactions and electrical properties of Hf/p-Si0.85Ge0.15 as a function of the annealing temperature were studied. Hf3(Si1-xGe)2 and Hf(Si1-xGe)2 were initially formed at 500°C and 600°C, respectively. At temperatures above 400°C, Ge segregation out of the reacted layers associated with strain relaxation of the unreacted Si0.85Ge0.15 films appeared. At 780°C, agglomeration occurred in the Hf(Si1-xGex)2 films. All the as-deposited and annealed Hf/p-Si 0.85Ge0.15 samples showed the formation of an ohmic contact. The lowest specific contact resistance around 10-5 Ω cm2 could be obtained for the Hf3 (Si1-xGex)2 contacts to p-Si0.85Ge0.15 formed at 500°C. Below 500°C, the decrease of specific contact resistance with the annealing temperature is mainly caused by the formation of Hf3(Si1-xGex)2 and an interfacial Ge-rich layer between the Hf3(Si1-xGex)2 and unreacted Si0.85Ge0.15 films, while above 600°C, the increase of specific contact resistance may be due to the formation of Hf(Si1-xGex)2 and SiC as well as the roughness of the Hf(Si1-xGex)2 films.