An amperometric flow-injection method for the determination of the antioxidants BHA, TBHQ and a mixture of them, using a 4-hydroxybenzaldehyde/formaldehyde polymer modified electrode is proposed. The procedure is based on the electrochemical oxidation in phosphate buffer solution (pH 7.2). Different analytical parameters and electrode stability were analyzed to obtain the best electrode performance, being the optimal conditions: working potentials 0.200 V and 0.700 V and flow rate 0.74 mLmin–1. The proposed method was used for antioxidants quantification in a cosmetic sun tanning lotion, without any previous sample treatment and mean recoveries of 104% were obtained. Interferences from other antioxidants (BHT and PG) were also analyzed and in all the cases, no synergic behavior was observed.