Abstract The oxidation of Ni II cyclam, Cu II cyclam (cyclam = [18]aneN 4 ) and Cu II CT (CT = Me 6 [14]-4,11-dieneN 4 ) by aquasilver(II) has been investigated kinetically in perchlorate media in the range [HClO 4 ] = 1–4 mol dm −3 . The reaction stoichiometry indicates 1 mol of oxidant reacting with 1 mol of M(II). Stopped-flow studies indicate a single reaction pathway involving M II L + Ag 2+ with k = 2.3 × 10 5 , 3.5 × 10 5 and 1.5 × 10 4 dm 3 mol −1 s −1 for Ni II cyclam, Cu II cyclan and Cu II CT respectively, at 10 °C. While Ni III cyclam is stable enough to allow UVVis characterization, Cu III cyclam and Cu III decay by a first-order process with rate constants of 1.5 and 0.053 s −1 respectively. Reliable kinetic results could not be obtained for the oxidation of Ni II CT by silver(II), but the oxidation product does, like Ni III cyclam, have a significant lifetime.