Wetting of vitreous carbon C-v by NiSi alloys is studied in high vacuum using the sessile drop and dispensed drop techniques. The role of reactions between NiSi and C-v (simple dissolution or SiC formation) on wetting, adhesion and mechanical behaviour of the interface is determined and discussed. The experimental results on reactive wetting are compared with the predictions of two different approaches proposed recently in order to explain the thermodynamics and kinetics of this type of wetting.