Quasi-reversible single electron transfer (ET) kinetics of methylviologen partly-included at the rim of 4-sulfonatocalix[n]arenes (n = 4,6 and 8) has been investigated in aqueous solution. ET rates were measured by Nicholson method with relatively large potential scan rates (0.9 V/s < v < 50 V/s). ET proceeded adiabatically on the direct collision between the MV+/MV2+ and the electrode surface. The host-guest binding equilibrium at the activation state was not established under the highspeed cyclic voltammetry condition. The non-equilibrium stabilization energy was independent of the size of the cavitands. The activation energy of ET under the partly-included condition was 70-80% of that without any inclusion.