Ahatract-A new type of macro-micrwmacro triple electrode has been fabricated, the steady-state currents of solution redox species have been observed at an ultramicroband electrode by linear potential scan voltammetry, and generation/collection experiments have also been performed at macro-micr+ macro triple and micro-micro twin electrodes. The electrochemical behaviour of a single reversible couple with a homogeneous catalytic reaction has been studied at each of the above two kinds of electrodes. We firstly obtained the kinetic equation based on a decrease of the collection current to determine the kinetic constant of the quasi-first-order homogeneous catalytic reaction, as (1 -i&)io = nFAD~12C,[( 1 + m)kC,]'l'
and we gave the experimental method to determine the kinetic constant. This method can be used with versatility to study homogeneous chemical reactions over a wide range of kinetic constants, which overcomes the disadvantage that an ultramicroelectrode is only suitable for fast catalytic reactions. Two systems, K,Fe(CN),-ascorbic acid and benxoquinone (Q) -0, were chosen to check the equation and to determine their kinetic constants.