Highly porous biomass-derived activated carbon was prepared by carbonisation of cherry laurel (Prunus laurocerasus L.) stone followed by chemical activation with zinc chloride (ZnCl2) at 700 degrees C. The resulting activated carbon was magnetised using a thermal process. The physicochemical properties of the magnetic activated carbon (AC/Fe3O4) were characterised by N-2 adsorption-desorption, X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy and vibrating sample magnetometer. The magnetic material exhibited a high specific surface area of 959 m(2)/g and a maximal saturation magnetisation of 28.5 emu/g. The AC/Fe3O4 was then used as an adsorbent for the magnetic solid-phase extraction of target herbicides (hexazinone, propachlor and prometryn) from environmental water samples followed by high performance liquid chromatography-ultraviolet detection. After optimising the main parameters in the extraction procedure, the extraction recoveries and preconcentration factors in the ranges of 71-84% and 18-21 were obtained, respectively. Good linearities were achieved with the coefficients of determination ranging from 0.9978 to 0.9997. The intra- and inter-day relative standard deviations were less than 5.2%. Limits of detection were obtained between 0.05 and 0.28 mu g/L. Finally, the proposed method was applied for the determination of the target herbicides in the environmental waters and satisfied recoveries between 71 and 101% were obtained from spiked samples.