Hydrogen represents one of the most attractive options for energy storage from renewables; it is the simplest and most abundant element on earth and has the highest energy density of any fuel. Driven by the goal of a zero-emission energy infrastructure by 2050, a green hydrogen economy is critical to enable a 100% renewable society. Currently, the greatest challenge for hydrogen production is the cost, which is not yet able to compete with conventional fossil fuels. Thus, a key direction in hydrogen energy research is focused on improving the efficiency and economic viability of hydrogen production technologies and materials. A promising pathway towards sustainable hydrogen production is water-based electrolysis, but a critical barrier for efficient water splitting is the high overpotential of the sluggish oxygen evolution reaction (OER) at the anode side of electrolyzer. Among non‐noble metals, transition metal chalcogenides have emerged as excellent options due to their superior electrocatalytic performances and better electrical conductivity and lower cost compared to most metal oxides and pure precious metals. However, irreversible restructuring is often observed in metal chalcogenide systems under oxidative OER conditions, leading to new phases that can sometimes outperform the material in its pristine state and creating a knowledge gap on what the real active phases of the catalyst are. As such, it is critical to identify the real active phases of metal chalcogenides to enable the rational design of electrocatalytic materials. While most of the focus has been on metal sulfides and selenides, this project is thus centered on elucidating the restructuring mechanism and true active phases of cobalt telluride materials, which has previously been shown to have excellent electrocatalytic performance and stability while being hypothesized to be more active than its sulfur and selenide counterparts to the higher electronegativity of tellurides.