Our research concentrates on zirconium diboride (ZrB2), a ceramic capable of withstanding extreme temperatures, pertinent to aerospace and nuclear sectors. Prior research has not addressed ZrB2's corrosion behavior in water vapor and oxygen at intermediate temperatures. Our study scrutinizes how ZrB2 behaves under regulated exposure to water vapor and oxygen, highlighting how a two-stage reaction influences its stability and suitability for industry. We assessed ZrB2 powder corrosion in deionized water at 190 ℃, utilizing a hydrothermal reactor for 0–2 days. This research deepens our understanding of ZrB2 reactivity, highlighting potential uses like hydrogen generation. It underscores the need for enhanced stability in reactive settings.