Abstract: An advance was made in the pretreatment of the powdered and homogeneized vermicelli sample by a reduction with 0.1 g of iron powder in 90 mL of 0.02 mol·L-1 NaOH solution to transform the benzoyl peroxide (BZPX) into benzoic acid (BZA).The acidity of the NaOH solution was neutralized to about pH 5 by adding 10 mL of a 0.02 mol·L-1 NH4OAc buffer solution (previously adjusted to pH 3.6 by glacial HOAC).The solution was filtered,separated on the Agilant Eclipse XDB-C18 column and finally measured at 230 nm with UV-detector.Range of linearity for the determination of benzoyl peroxide (in the form of benzoic acid) was found form 1-50 mg·L-1 (r=0.999 9) with a detection limit of 0.2 mg·L-1 (S/N=3).Test for precision and recovery gave values of RSD′s (n=6) in the range of 1.49%-4.61% and values of recoveries in the range from 88.0% to 97.5%.