This study was undertaken to establish the weldability of a high pressure steam turbine rotor (1.0Cr-1.0Mo-0.25V steel). Characterization of the as-received material and subsequent evaluation of a de-embrittlement procedure suggests that such heat treatment should be carried out prior to welding. But the improvement in toughness experienced by the heat affected zone (HAZ) of welds produced on both as-received and de-embrittled steel coupons suggests that a preweld de-embrittlement treatment is unnecessary. Further, a postweld heat treatment (PWHT) at the optimum temperature was found to improve the impact properties of both the HAZ and the base metal. The welds were automatically made on steel coupons with the welding parameters held constant, controlled by a microprocessor. In terms of short-term mechanical properties, the turbine rotor can be weld repaired. Studies are presently being conducted under simulated service conditions for long-term testing.