Semiconductors for high temperature become increasingly important for automotive applications and power devices. High thermal interconnection technology is requested. Commercial 4N gold wire (purity>99.99%) caused a bond corrosion problem at elevated temperatures. Thermal bond reliability of gold alloy wire was investigated with HP alloy wire and LP alloy wire which include high and low concentration palladium, respectively. The bond strength of HP wire declined faster than 4N wire after aging at 423K. There were Pd-enriched compound and cracking at bond interface of HP wire. LP wire can exceed the target of 423K-2000hr for reliability testing. The alloy wire was also suitable for fine pitch bonding. In this paper, bond failure mechanism was clarified and high thermal reliability bonding wires developed were shown.