The oxidation behavior of iodide has been investigated by linear sweep voltammetry and cyclic voltammetry at a platinum electrode in the room temperature ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroborate ([C(4)mim][BF4]). The experimental results showed that iodide yielded two oxidation peaks P-a1 and P-a2 in [C(4)mim][BF4], and both of P-a1 and P-a2 are diffusion-control led. P-a1 yielded from iodide to triiodide at +0.58 V is a two-electron oxidation wave, and P.2 yielded from triiodide to iodine at +1.00 V is one-electron oxidation wave. Linear relationships between 1(pal) and the concentration of iodide can be established from 0.45 to 7.2 mmol L-1 with a detect limit of 0.3 mmol L-1 by linear sweep voltammetry, and from 0.30 to 7.8 mmol L-1 with a detect limit of 0.2 mmol L-1 by differential pulse voltammetry. These methods can be used for simple, rapid determination of iodide in the crude [C(4)mim][BF4]. (c) 2006 Elsevier Ltd. All rights reserved.