Adducts of hydrogen peroxide and transition metals have been implicated as intermediates in biological and industrial processes but have only recently been observed. Therefore, knowledge of how hydrogen peroxide interacts with transition metals is extremely limited. Herein, we report the synthesis of H2O2 complexes of cobalt, nickel, and copper supported by sulfonamido ligands with second-sphere hydrogen bonding. Binding constant and decay kinetics are reported for four new M(H2O2) adducts, providing a foundation for future studies in H2O2 coordination and oxidation catalysis.