Abstract: A method of photo-oxidizing a hydrocarbon compound is provided by dispersing MoS2 nanoclusters in a solvent containing a hydrocarbon compound contaminant to form a stable solution mixture and irradiating the mixture to photo-oxide the hydrocarbon compound. Hydrocarbon compounds of interest include aromatic hydrocarbon and chlorinated hydrocarbons. MoS2 nanoclusters with an average diameter less than approximately 10 nanometers are shown to be effective in decomposing potentially toxic aromatic and chlorinated hydrocarbons, such as phenol, pentachlorophenol, chlorinated biphenols, and chloroform, into relatively non-toxic compounds. The irradiation can occur by exposing the MoS2 nanoclusters and hydrocarbon compound mixture with visible light. The MoS2 nanoclusters can be introduced to the toxic hydrocarbons as either a MoS2 solution or deposited on a support material.