This study investigated the effects of the initial Ce(III) concentration, nitric acid concentration, anion impurity, and cell device on Ce(IV) regeneration in simulated spent Cr-etching solutions from thin-film transistor liquid crystal display manufacture. Increasing HNO3 (electrolyte) concentration (0.5-4 M) favored 0.2 M Ce(III) electro-oxidation, Ce(III) diffusion [(0.37-3.32) x 10(-6) cm(2) s(-1)], and internal cell resistance reduction. The amount of Ce(IV) regenerated from Ce(III) electro-oxidation and the current efficiency (CE) at 0.13 A cm(-2) electrolysis on Pt increased with increasing initial Ce(III) concentration in 4 M HNO3 without impurities in a divided cell with an anion-exchange (AMI-7001) separator. Both Ce(IV) yield and CE were lowered in the copresence of multiple impurities, and the adverse influence of a single anion impurity on the Ce(IV) yield and CE was in the order Cl- > SO42- > Cr2O72-. The apparent rate constant of Ce(III) oxidation without impurity (1.32 x 10(-4) s(-1)) was approximately fourfold that with multiple impurities; nevertheless, the two cases exhibited similar Ce(IV) yields or CEs at 0.13 A cm(-2) electrolysis for 300 min. For the Ce(IV) regeneration, the divided cell was superior to an undivided cell in the absence/presence of multiple impurities, and the AMI-7001 was better than a cation-exchange separator (CMI-7000). (C) 2009 The Electrochemical Society. [DOI: 10.1149/1.3236628] All rights reserved.