The focus of this work is to report on the preparation of MgO buffer layers on GaAs. Successful deposition of buffer layer materials for the YBa2Cu3Ox high-temperature superconductor has been obtained. MgO layers were grown by pulsed DC magnetron sputtering under various experimental conditions. Crystallinity, stoichiometry and growth rate are sensitive to temperature (100-600 degrees C) and oxygen pressure (0.1-1.0 mTorr). The room-temperature resistivity of the MgO films is in the range of 10(11) Omega cm. Residual stresses are measured with a Tencor FLX 2320 for the various experimental conditions to investigate the MgO lattice mismatch to GaAs. Capacitance-voltage measurements indicate a qualitative difference in the interfacial electronic properties with substrate surface treatments.