In this study, magnetic activated carbons were produced from activated carbon, and the adsorption capacities of both were determined. The adsorption experiments were carried out as a function of initial concentration, pH and time. The adsorption kinetic data were well-described by the Lagergren first-order model. The kinetic studies showed that the adsorption rates were controlled by both film and intra-particle diffusion. The adsorption equilibrium data demonstrated that the adsorption of phenol red on activated and magnetic activated carbons followed the Langmuir isotherm. The adsorption capacities of all the adsorbents decreased significantly with increasing pH values.