The catalytic properties of peroxidase basic isoenzymes (PBIs) from Brassica napus towards trans-resveratrol (t-Res) oxidation were demonstrated by the first time by conventional UV-visible spectroscopic measurements. The enzymatic reaction rate was studied under different experimental conditions and the kinetics parameters were determined. An amperometric biosensor based on Brassica napus PBIs to determine t-Res is also proposed by the first time. The method employs a dialysis membrane covered, PBIs entrapped and ferrocene (Fc)-embedded carbon paste electrode (PBIs-Fc-CP) and is based on the fact that the decreased amount of H 2 O 2 produced by the action of PBIs is proportional to the oxidised amount of t-Res in the solution. Comparative amperometric experiments showed that, in spite of PBIs activity was much lower than commercial horseradish peroxidase (HRP) activity, t-Res was a much better substrate for PBIs biosensors than those biosensors constructed by using HRP. The PBIs-Fc-CP biosensors showed a very good stability during at least twenty days. The reproducibility and the repeatability were 4.5% and 8.3%, respectively, showing a good biosensor performance. The calibration curve was linear in the t-Res concentration (c t-Res ) range from 1 Â 10 À6 to 2.5 Â 10 À5 M, with a sensibility of (2.31 AE 0.05) Â 10 6 nA M
À1. The lowest c t-Res value measured experimentally for a signal to noise ratio of 3 : 1 was 0.83 mM.