The adsorption of phenol, p-chlorophenol and p-nitrophenol onto granular activated carbon (GAG) in a liquid-solid fluidized-bed adsorber has been studied. The effects of particle sizes of activated carbon (0.937, 1.524 mm), liquid flow rate (1.2, 2.0, 4.0 dm(3) min(-1)), initial phenol concentrations (1.12 x 10(-4) 5.88 x 10(-4) mol dm(-3)) and activated carbon mass (75, 150, 300 g) were investigated. The isotherm data were analysed by using the well-known isotherm equations to realize the adsorption characteristics of granular activated carbon. The model, which takes into account the external mass transfer with film-surface diffusion, surface adsorption equilibrium and internal mass transfer, was employed to fit the experimental data of the breakthrough curve. The model agreed with the experimental results very well when the Langmuir isotherm was employed and can be used for design and parametric studies.