The SCC growth rates of 316L weld heat-affected zone (HAZ) and weld metal materials in 288°C pure water were measured. The effects of loading mode and dissolved oxygen on crack growth rate (CGR) were experimentally quantified. Typical intergranular SCC was found in the HAZ specimen, and interdendritic SCC was identified in the weld metal specimen. The HAZ specimen and the weld metal specimen showed quite a similar response to the applied loading modes and the water chemistry, even though their absolute CGR values are different. The crack growth rates under trapezoidal loading are moderately higher than those under constant loading. Switching from the oxygen-bearing water to the hydrogen-bearing water drastically decreased the electrochemical potential and CGR. A time-lag period for crack growth was observed after switching the hydrogenated water back to the oxygen-bearing water, where CGR was low even after the dissolved oxygen concentration and the electrochemical potential had become high.