The theory for the analysis of redox enzymatic activity, under the condition of enzymatic substrate saturation, in SECM feedback mode has been reexamined. The conditions of validity for the different limiting cases have been established and discussed. Thanks to this analysis, we present different methods for determining the kinetics parameters from approximate analytical expressions without having to return to the numerical simulations. It was found that real zero order does not really exist, as first-order behaviour is always present at substrate sufficiently far from the center of the electrode. (C) 2009 Elsevier B.V. All rights reserved.