Wetting of molten Ni-56 at.% Si alloy on different substrates (SiC ceramic, Ni- and Co-based superalloys, Kovar, and Mo) are performed under different experimental conditions by the sessile drop technique. Temperature, atmosphere, and substrate composition play the key roles in determining the wettability, the spreading characteristics, and the interfacial morphology of the final interfaces. The non-reactive wetting characteristics in Ni-Si/SiC system are confirmed, with a spreading rate increasing with temperature increasing. In the Ni-Si/metal systems the spreading process is determined by the competition between spreading along the substrate surface and the interfacial interactions. Excellent wettability and fast spreading are found in the Ni-Si/Co-based superalloy, Ni-Si/Kovar, and Ni-Si/Mo systems at both the temperatures (1100 and 1200 A degrees C). These results can be used as a reference guide for joining SiC to these metallic components, or to itself, using the Ni-Si alloy as filler metal.