Fuel oil fly ash has been tested as low-cost carbon-based adsorbent of 2-chlorophenol (CP), 2-chloroaniline (CA) and methylene blue (MB) from aqueous solutions. In all the cases the adsorption was found to be of cooperative type. Different adsorption capacities were found for the three organics. Specifically, it was highest for 2-chlorophenol, reaching about 70 mg g(-1), and quite lower in the other two cases, that is about 47 and 36 mg g(-1) for methylene blue and 2-chloroaniline, respectively. Varying the initial pH and adding KCl were found to have different effects on the adsorption of the three organics. In particular, the presence of other ions had no effect on the adsorption of methylene blue, adverse effect in the case of 2-chlorophenol and enhancing effect in the case of 2-chloroaniline.