Materials and processes are being developed for packaging of low and medium power, high temperature electronics (up to 500^o). Ceramic (Al₂O₃ and AlN) hermetic packages are being used. Die attach techniques based on Au bump thermocompression, Au-Si and off-eutectic Au-Sn have been demonstrated. Au thermosonic wire bonding provides a monometallic interconnect system between the die and the package pads. Both metallized ceramic and metal lids were vacuum solder sealed with off-eutectic Au-Sn. The sealing process had to be optimized to prevent growth of Ni-Sn-Au crystals during the liquidus phase of the sealing process. Assembly process details and initial characterizations results are presented.