Al-Si wires are often used to make contact to bond-pads of semiconductor chips and devices. During operation in certain types of devices the wires typically reach relatively high temperatures. Under such circumstances, the oxidation could lead to a decrease of wire conductivity. It is of interest therefore to understand the oxidation behavior of the bond wires, particularly at elevated temperatures. In the current study, Al-Si wires were characterized as received from the supplier, and after thermal annealing at 240°C and 300°C. The surface oxides were found to evolve from a single-layer oxide to a double-layer oxide with varying chemistry. Oxide thicknesses were substantially lower than the wire diameter, even after 3000 hours of annealing. Therefore oxidation of the Al-Si wires has an insignificant impact on their electrical conductivity.