This communication presents our recent results that the activity of photocatalytic H-2 production can be significantly enhanced when a small amount of MoS2 is loaded on CdS as cocatalyst. The MoS2/CdS catalysts show high rate of H-2 evolution from photocatalytic re-forming of lactic acid under visible light irradiation. The rate of H-2 evolution on CdS is increased by up to 36 times when loaded with only 0.2 wt % of MoS2, and the activity of MoS2/CdS is even higher than those of the CdS photocatalysts loaded with different noble metals, such as Pt, Ru, Rh, Pd, and Au. The junction formed between MoS2 and CdS and the excellent H-2 activation property of MoS2 are supposed to be responsible for the enhanced photocatalytic activity of MoS2/CdS.