This study investigated regeneration of Ce(IV) from Ce(III) oxidation at 0.05-0.5A cm(-2) in 4M HNO3 with/without anion impurities (SO42-(0.01-0.2 M), Cl- (0.01-0.08 M), and/or Cr2O72- (0.005-0.016 M)) in an undivided cell. Both Ce(IV) yield and current efficiency (CE) were significantly lower in 0.1 M than in 1-4 M HNO3 and different on anode materials (in order Pt > IrO2/Ti > glassy carbon). The apparent rate constants for Ce(III) oxidation on the Pt anode (k(1)) and for Ce(IV) reduction on a stainless steel cathode (k(2)) were (0.40-1.80) x 10(-4) and (0.08-1.01) x 10(-4) s(-1), respectively, corresponding to the apparent mass transfer coefficients of (2.0-9.0) x 10(-3) and (0.4-5.1) x 10(-3) cm s(-1), respectively. For Ce(III) oxidation at 0.3 A cm(-2) in 4 M HNO3 containing multi-impurity (0.025 M SO42- + 0.08 M Cl- + 0.016 M Cr2O72-), the k(1) was lowered by one order of magnitude although the k2 remained unchanged, and both Ce(IV) yield and CE were reduced by similar to 89%. The decrease of Ce(IV) yield and CE by the uni-impurity was in order Cl- > Cr2O72- > SO42-. The obtained parameters are useful to design undivided batch reactors for the Ce(IV) electro-regeneration in spent Cr-etching solutions. (C) 2009 Elsevier B.V. All rights reserved.