The kinetics of the Yb(III)/Yb(II) couple in aprotic solvents are rapid at several electrode materials and the reducing power of the Yb(II) may be modified substantially by choice of solvent and electrolyte. Electrogenerated Yb(II), when present in stoichiometric amounts, allows the stereoselective reduction of 1,3-dibenzoylpropane to the cis isomer of a cyclic diol. Ytterbium(III) is not, however, a straightforward 'mediator' because, after the reduction of 1,3-dibenzoylpropane by the Yb(H), the Yb(III) is bound to the organic product. Both use of an aluminium anode or addition of trimethylsilylbromide lead to release of the Yb(III); then the ytterbium acts as a catalyst. Such procedures, however, lead to loss in the stereoselectivity of the reduction and the reactions are slow so that the regeneration of the Yb(III) does not enhance the current density. The current density is always low, limited by mass transport of the catalyst. (C) 2003 Elsevier Science Ltd. All rights reserved.