Calcium peroxide ( \({\text{CaO}}_{2}\) , CP) has emerged as a versatile oxidant for environmental remediation due to its ability to release hydrogen peroxide (HP, \({\text{H}}_{2}{\text{O}}_{2}\) ) in a controlled manner. Its solid-state form offers advantages in storage and handling compared to liquid \({\text{H}}_{2}{\text{O}}_{2}\) , while its effectiveness across a wide pH range makes it suitable for advanced oxidation processes (AOPs). \({\text{CaO}}_{2}\) has been widely applied in the degradation of persistent organic pollutants in water and soil. The efficiency of \({\text{CaO}}_{2}\) based systems is strongly influenced by operational parameters such as pH, initial oxidant and catalyst concentrations, and temperature. Acidic conditions promote rapid \({\text{H}}_{2}{\text{O}}_{2}\) generation, whereas neutral conditions allow sustained oxidant release, enhancing Fenton-type processes. Nanostructured \({\text{CaO}}_{2}\) further improves performance by increasing surface area and facilitating reactive oxygen species (ROS) generation. This review discusses the synthesis and characterization of \({\text{CaO}}_{2}\) nanoparticles (NPs), methods to determine purity and oxygen release, optimization of operational parameters, enhancement strategies for \({\text{CaO}}_{2}\) based oxidation systems, investigation of ROS, and degradation kinetics. Overall, CaO₂ represents a stable, efficient, and versatile oxidant, providing sustained ROS release and effective removal of persistent organic pollutants for sustainable environmental remediation.
