The adsorption of two non-steroidal anti-inflammatory drugs (NSAIDs), namely naproxen and ketoprofen, has been studied. Low-cost carbonaceous materials such as carbon blacks have been used as the adsorbents. The influence of temperature (20-60 degrees C), pH (3-11), ionic strength (0.01-0.1 M), textural properties of the adsorbents (S-BET and pore volumes) and aqueous matrix on the adsorption process has been analyzed. The adsorption isotherms have been determined both in milli-Q (TM) aqueous solution and water from the Guadiana river. Ionic strength and pH exert a noticeable influence on the process. In general, the removal is favored at low values of temperature and pH. On the contrary, an increase of the ionic strength seems to favor the adsorption process. The use of more porous adsorbents results in a more effective removal of the pollutants. Finally, the use of natural river water results in a noticeable increase of the removal capacity of naproxen and, particularly, ketoprofen. The experimental results proved that, under the optimal operation conditions, up to 517 mg/g of naproxen and 400 mg/g of ketoprofen may be adsorbed, which demonstrates the promising potential of these adsorbents for the removal of the pharmaceuticals under study. (C) 2010 Elsevier By. All rights reserved.