The interface chemistry of nickel and tungsten based contacts on SiC has been investigated by XPS on as-deposited samples and after contact formation. After annealing at 950 degrees C for 10 min, Ni/SiC and Ni/Si/SiC ohmic contacts are formed due to the chemical reactions, as a result of which Ni,Si appears. However, Ni/Si (instead of pure Ni) deposition on SiC leads to modification of the diffusion processes and formation of a contact layer free of carbon. After annealing at 1200 degrees C for 4 min, the WN (W)/SiC systems are characterized by strong interface reactions resulting in W5Si3 and W2C formation in the contact layer. The 800 degrees C annealed WN/SiC contact is characterized by a chemically inert interface, and is found to be of a Schottky type.