An efficient arylation/C-C activation process was discovered. beta-Diketones with aryl halides (aryl iodides and aryl bromides) could undergo reaction smoothly in the presence of Cu(I) or Cu(II) salts in DMSO using K3PO4 center dot 3H(2)O without ligands. The role of H2O was unprecedented, which assisted the C-C activation. Various a-aryl ketones could be efficiently synthesized by this novel method. In situ monitoring of the formation of KOAc and experimentation relating to "a classic diagnostic technique for the participation of radical anion intermediates" revealed the preliminary mechanistic information for the reaction. This method is simple, general, and practical which complemented the classic method for the rapid construction of C-C bonds to a carbonyl moiety.