The phases occurring upon lead free soldering of copper substrates using indium, which contains for improved wetting additions of Ti, belong to the ternary system Cu-In-Ti. Thus, the liquidus surface of the ternary system Cu-In-Ti is determined using DTA data. Alloys were prepared from high purity metals by arc melting under pure argon. Before measuring the heating curves, all alloys were equilibrated at appropriate temperatures and XRD phase analysis were performed. A reaction scheme linking the phase equilibria found in the annealed alloys to the liquid phase is obtained. A projection of the resulting liquidus surface, which is dominated by the primary crystallisation field of the congruently melting Heusler phase t1-Cu2TiAl, is presented. In the In-rich composition corner the liquid phase solidifies in a ternary eutectic (In) + Ti2In5 + Cu11In9 at 155°C.