The new welding material – ERCuTi alloys filler metals were developed specially for gas tungsten arc welding (GTAW) of copper. The hot cracking in welding copper is inhibited completely as the addition of de-oxidant element Ti in copper welding material. The degree of addition of Ti (2-4wt%) is critical when the susceptibility of cracking is to be suppressed. If the level is allowed to exceed 4wt%, more low-melting point eutectics (β-TiCu4 and TiCu2) will be formed in the welds, and cracking susceptibility will be increased again. Results of mechanical properties tests show that although adding Ti increases the hardness and strength of the weld compared to the base metal, the impact ductility and the plastic properties are not decreased significantly.