Peroxidases are multifunctional enzymes present in all land plants, belonging to a large multigenic family. They are involved in a wide range of physiological processes throughout the plant life cycle, including cell wall modification, regulation of H₂O₂ levels, and defense against biotic and abiotic stresses. Peroxidases can generate reactive oxygen species (ROS), such as hydroxyl radicals (·OH) and hydrogen peroxide (H₂O₂), and participate in both peroxidative and hydroxylic catalytic cycles. These cycles allow peroxidases to either polymerize cell wall compounds or regulate ROS levels, contributing to plant growth and development. The enzyme's functions include building rigid cell walls, producing ROS for flexibility, and defending against pathogens through physical barriers or ROS production. They are also involved in symbiotic relationships. The number of peroxidase genes has increased with plant evolution, possibly due to the complexity of plant architecture and the diversity of biotopes and pathogens. The gene structure and key amino acid residues are highly conserved among orthologs and paralogs, but their isoelectric points vary. The high number of paralogs in plants like Arabidopsis and rice is linked to gene duplication and conservation. The hydroxylic cycle, which produces radical species, expands the range of peroxidase functions. Peroxidases are active throughout the plant's life, from germination to senescence, playing roles in cell elongation, defense, and other processes. Their involvement in ROS production and signaling pathways highlights their importance in plant physiology. This review discusses the factors influencing the delicate balance of peroxidase functions. Keywords: Evolution, ROS, stress, cell wall loosening, senescence, fruit ripening, symbiosis.Peroxidases are multifunctional enzymes present in all land plants, belonging to a large multigenic family. They are involved in a wide range of physiological processes throughout the plant life cycle, including cell wall modification, regulation of H₂O₂ levels, and defense against biotic and abiotic stresses. Peroxidases can generate reactive oxygen species (ROS), such as hydroxyl radicals (·OH) and hydrogen peroxide (H₂O₂), and participate in both peroxidative and hydroxylic catalytic cycles. These cycles allow peroxidases to either polymerize cell wall compounds or regulate ROS levels, contributing to plant growth and development. The enzyme's functions include building rigid cell walls, producing ROS for flexibility, and defending against pathogens through physical barriers or ROS production. They are also involved in symbiotic relationships. The number of peroxidase genes has increased with plant evolution, possibly due to the complexity of plant architecture and the diversity of biotopes and pathogens. The gene structure and key amino acid residues are highly conserved among orthologs and paralogs, but their isoelectric points vary. The high number of paralogs in plants like Arabidopsis and rice is linked to gene duplication and conservation. The hydroxylic cycle, which produces radical species, expands the range of peroxidase functions. Peroxidases are active throughout the plant's life, from germination to senescence, playing roles in cell elongation, defense, and other processes. Their involvement in ROS production and signaling pathways highlights their importance in plant physiology. This review discusses the factors influencing the delicate balance of peroxidase functions. Keywords: Evolution, ROS, stress, cell wall loosening, senescence, fruit ripening, symbiosis.