Supercritical water oxidation (SCWO) is a technology which can effectively destroy civilian and military wastes by oxidation in water at high temperature and pressure (T approximate to 550 - 650 degrees C, 250 bar). Surmounting the problems of severe degradation of the materials of construction is, however, a pivotal issue in the development of scaled-up systems. High-nickel alloys are important for severe service; however, results indicate they will not survive certain SCWO environments. Although exotic liners such as platinum are currently promoted as a solution to aggressive conditions, this paper provides evidence suggesting it may ultimately be possible to use more conventional materials.