Silver-copper-titanium (Ag-Cu-Ti) ternary alloys are often used as active braze alloys for joining ceramics to metals at temperatures ranging from 780°C (the melting point of the Ag-Cu eutectic) up to 900°C. When Ti/Ag-Cu joints are brazed at low temperature (near 800°C), the intermetallic compound Ti 2 Cu 3 (tetragonal, P4/nmm, a = 0.313 nm, c = 1.395 nm) is systematically missing from the interface reaction layer sequence. An experimental investigation based on isothermal diffusion experiments in the Ag-Cu-Ti ternary system has then been undertaken to clarify the issues of thermal stability and formation kinetics of this compound. Evidence has been found for the stability of Ti 2 Cu 3 at temperatures ranging from 790 to at least 860°C. By heat treating Ag-Cu-Ti powder mixtures at 790°C for increasing times, it has moreover been shown that Ti 2 Cu 3 forms at a much slower rate than the two adjacent Ti-Cu compounds: TiCu 4 , the first phase to form, and Ti 3 Cu 4 . This explains why although thermodynamically stable, Ti 2 Cu 3 is not obtained when temperature is too low or reaction time too short.