The adsorption of three phenolic compounds from aqueous solutions on activated carbon fibers was measured in the 2–5 mol/m concentration range at 303 K. High adsorption capacities were obtained for the substituted phenols. Several isotherm equations were tried in order to find an equation which correlates the equilibrium data best. Among the equations tried, the three-parameter equation of Jossens et al. derived thermodynamically and based on a heterogeneous surface adsorption theory was found to be the most satisfactory over the entire range of concentrations. A rate parameter was obtained and used to describe the adsorption process on a quantitative basis. This rate parameter could be successfully correlated against the initial solute concentration.