Activated carbons were prepared from eucalyptus wood, by using three different “physical” activating methods: air and CO₂ partial gasification of wood char (2 hr, 400°C and 800°C, respectively), and direct CO₂ partial gasification of wood sawdust. The three activated carbons were then oxidized with HNO₃ for increasing the surface concentration of oxygenated functions, and Cr(III) aqueous solution adsorption isotherms were determined for each oxidized carbon. Characterization of the carbons were done through elemental analysis, N₂ adsorption, and Fourier transform infrared spectroscopy spectra. Results show that oxidized activated carbons prepared from air gasification have the higher Cr(III) adsorption capacity. Conclusions about chemical functions formed onto the carbon surface and the relationship with Cr(III) adsorption are exposed.