This article reviews the developments and perspectives of oxide-based catalysts for the oxygen evolution reaction (OER) in water electrolysis. The OER is a critical step in water electrolysis, which is essential for converting renewable energy into chemical energy. High-efficiency and stable OER catalysts are crucial for the widespread adoption of water electrolyzers. Recent advancements in theoretical tools and computational studies have provided significant insights into the atomic-level understanding of the OER and electrocatalyst behavior. Experimental studies have also explored new catalytic materials with advanced properties and kinetics. The article discusses the challenges and requirements for OER catalysts, including high catalytic activity, stability, and selectivity. It highlights the importance of understanding the rate-determining step (RDS) and the potential-determining step (PDS) in the OER mechanism. The binding energy of reaction intermediates and the presence of anion adsorbates are also critical factors. The nature of the electrochemical interface, such as metallic or semiconducting properties, affects the performance of the catalyst. The article reviews the performance of various single metal-(oxide) electrocatalysts, focusing on their catalytic activity and stability. Ruthenium oxide (RuO2) is recognized as the most active single metal-oxide catalyst, but it lacks stability. Iridium oxide (IrO2) is a better alternative due to its higher stability, but it is less active. The article also discusses the use of bimetallic (oxide) electrocatalysts, such as Ru-Ir alloys, to combine the advantages of both materials. Overall, the article provides a comprehensive overview of the current state of oxide-based OER catalysts, highlighting the ongoing research efforts to improve their performance and stability for practical applications in water electrolyzers.This article reviews the developments and perspectives of oxide-based catalysts for the oxygen evolution reaction (OER) in water electrolysis. The OER is a critical step in water electrolysis, which is essential for converting renewable energy into chemical energy. High-efficiency and stable OER catalysts are crucial for the widespread adoption of water electrolyzers. Recent advancements in theoretical tools and computational studies have provided significant insights into the atomic-level understanding of the OER and electrocatalyst behavior. Experimental studies have also explored new catalytic materials with advanced properties and kinetics. The article discusses the challenges and requirements for OER catalysts, including high catalytic activity, stability, and selectivity. It highlights the importance of understanding the rate-determining step (RDS) and the potential-determining step (PDS) in the OER mechanism. The binding energy of reaction intermediates and the presence of anion adsorbates are also critical factors. The nature of the electrochemical interface, such as metallic or semiconducting properties, affects the performance of the catalyst. The article reviews the performance of various single metal-(oxide) electrocatalysts, focusing on their catalytic activity and stability. Ruthenium oxide (RuO2) is recognized as the most active single metal-oxide catalyst, but it lacks stability. Iridium oxide (IrO2) is a better alternative due to its higher stability, but it is less active. The article also discusses the use of bimetallic (oxide) electrocatalysts, such as Ru-Ir alloys, to combine the advantages of both materials. Overall, the article provides a comprehensive overview of the current state of oxide-based OER catalysts, highlighting the ongoing research efforts to improve their performance and stability for practical applications in water electrolyzers.