We present an efficient mathematical framework to determine the potential-dependent transition states of electron transfer reactions by quantum calculations. This approach makes it more feasible to study heterogeneous electron transfer processes with the theory of local reaction center for electron transfer. It is shown that the new formulation regenerates previously published results obtained by the constrained variation method. Our solution algorithm replaces the constrained optimization problem defined in a multidimensional space by a single equation in terms of only one variable that is solved for in each iteration. This method leads to fast convergence, reliability, and robustness of the located transition states for more complex systems with a larger number of degrees of freedom, especially for smooth energy surfaces. (c) 2006 The Electrochemical Society.