This study is related to reactivity of dioxygen bridged palladium complexes having ${pi}$-allyl ligands. In this case, new dioxygen bridged palladium complexes were prepared using superoxide ion$(O_2^-)$ as an oxygen source. Reactions of the dioxygen palladium complexes prepared in the study were examined in order to clarify the nature of the coordinated dioxygen. Treatments of a solution of the dioxygen bridged palladium complexes in benzene by water, methanol and acetic acid gave hydrogen peroxide $(H_2O_2)$ as hydroxy-, methoxy-, and acetoxybridged palladium complexes, respectively. The dioxygen bridged palladium complexes reacted also with substitution phenols of salicylaldehyde, 8-hydroxyquinoline and active methylenes of acetylacetone, dimethyl malonate to afford mononuclear complexes of palladium and hydrogen peroxide. The results suggest that dioxygen is coordinated as peroxo $(O_2^{2-})$ in the complexes and behaves as a strong base