The potential of Er-doped AlxIn0.1 Ga 0.9-xN quaternary alloys as high-temperature thermoelectric (TE) materials has been explored. It was found that the incorporation of Er significantly decreased the thermal conductivity (κ) of Al xIn0.1Ga0.9-xN alloys. The temperature- dependent TE properties were measured up to 1055 K for an Er and Si co-doped n-type Al0.1 In0.1 Ga0.8N alloy. The figure of merit (ZT) showed a linear increase with temperature and a value of about 0.3 at 1055 K was estimated. The ability to survive such high temperature with reasonable TE properties suggests that low-In-content Er and Si-doped AlInGaN alloys are potential candidate of high-temperature TE materials.