The present study introduces for the first time the effect of the cationic surfactant, cetyltrimethylammonium bromide (CTAB) on the adsorption capability of the boron-doped diamond (BDD) electrode for the sensing of environmental pollutants bisphenol A (BPA) and hydroquinone (HQ). Cathodic pretreatment of the electrode surface after an anodic pretreatment exhibited a best electrochemical response for these two phenolic compounds. The electrochemical characteristics of BPA and HQ were first sufficiently documented by cyclic voltammetry in aqueous solutions without the addition of surfactant over a shorter and longer potential range. Square-wave voltammetry was employed for a detailed study depending on the operational conditions (e.g., pH and nature of supporting electrolyte, concentration of CTAB, accumulation variables, instrumental parameters, etc.). The sensitivity of the voltammetric measurements for BPA and HQ was increased when CTAB was present in strong acidic media (more effective for BPA) due to its interaction with the neutral forms of the selected compounds on the hydrophobic surface of BDD electrode. Besides, a significant increase in the detecting sensitivity of BPA in CTAB-containing solutions could be obtained after applying an accumulation process. Using square-wave stripping mode (after 30 s accumulation at open-circuit condition) in 0.1 M H2SO4 containing 1 x 10(-4) M CTAB, the limits of detection were found to be 0.05 mu g/mL (2.19 x 10 M), and 0.23 tig/mL (2.09 x 10(-6) M) for the simultaneous determination of BPA and HQ, respectively. In this way, modification-free BDD electrode could introduce an alternative to chemically modified electrodes for the analysis of environmental samples.