Graphitic carbon nitride (g-C3N4) was synthesized by directly thermal condensation of dicyandiamide and characterized by XRD, XPS, SEM, TEM and FT-IR. Then the as-prepared catalyst was employed to degrade priority pollutant 2,4,6-trichlorophenol (2,4,6-TCP) under visible light irradiation (lambda > 420 nm). The 2,4,6-TCP could be completely mineralized over g-C3N4, and the pseudo-first-order rate constant for 10(-4) M 2,4,6-TCP degradation was 0.70 h(-1) in the presence of 1 g/L catalyst. O-center dot(2)-/(OOH)-O-center dot was identified as the most important reactive species contributing to 2,4,6-TCP degradation in air. Meanwhile, valence band holes (VB holes) of g-C3N4 was observed to play important roles for the degradation of 2,4,6-TCP at N-2 gas ambient when metal ions were added as electron acceptors. The possible degradation pathway of 2,4,6-TCP was proposed. (C) 2012 Elsevier B.V. All rights reserved.