A simple and highly sensitive electrochemical method for the simultaneous and quantitative detection of ascorbic acid (AA) and rutin was developed, based on an acetylene black paste electrode coated with cetyltrimethyl ammonium bromide film (denoted as CTAB/ABPE). In 0.1 mol L-1 HCl aqueous solution, the prepared modified electrode showed higher accumulation efficiency toward AA and rutin compared with bare ABPE, and significantly enhanced the peak currents of AA and rutin. The difference of the anodic peak potentials between AA and rutin was about 350 mV, which is large enough to determine AA and rutin individually and simultaneously. The electrochemical behaviors of AA and rutin were carefully investigated with the electrochemical parameters calculated. Under optimized conditions, the linear calibration ranges were 2.0 x 10(-6) M to 1.0 x 10(-3) M for AA and 6.0 x 10(-9) M to 1.0 x 10(-5) M for rutin, and the detection limits (S/N = 3) were 1.0 x 10(-6) M and 4.0 x 10(-9) M, respectively. This modified electrode was applied to direct simultaneous determination of AA and rutin in the selected pharmaceutical samples without previous chemical or physical separations. Moreover, the CTAB/ABPE offers some advantages including low cost, facility of construction, good reproducibility and high stability. (C) 2012 Elsevier B.V. All rights reserved.