Fenton-treated diamond (D) nanoparticles (NPs) are suitable support of gold to promote the wet peroxidation of phenol by H2O2. One of the drawbacks of this catalyst is the need of the pretreated commercial D NPs with a large excess of H2O2 and Fe(II) salts to remove the accompanying soot matter and introduce surface -OH groups on D. This process generates a large amount of waste waters and consumes large quantities of reagents, being desirable to develop alternative pretreatments for commercial D NPs. In the present manuscript we describe that a light combustion of the soot matter in a furnace under controlled temperature and time leads to a D support that after annealing at 500 degrees C under hydrogen affords a modified D material that is suitable as support of gold. We have found that annealing with hydrogen produces more efficient D samples than those without annealing or submitted to annealing under nitrogen. Characterization of the samples has shown that hydrogen annealing reduces surface C=O bonds to alcohols that are beneficial for anchoring gold nanoparticles. In this way, the resulting gold catalyst can set off the disappearance of phenol in water at pH 4 with only 2.6 equiv. of H2O2 assisted by Sunlight. (c) 2013 Elsevier B.V. All rights reserved.