The molecular dynamics of thiophene in its neat liquid and in binary solutions with carbon tetrachloride of various mole fractions has been investigated by means of optically heterodyned optical Kerr effect (OHD-OKE) experiment. An unusual increase in orientational relaxation time at the specific mole fraction of thiophene (approximate to 0.7) was observed and it is suggested that the relaxation process is influenced by the complex formation between thiophene and carbon tetrachloride. The concentration dependence of the instantaneous third-order susceptibility is also discussed.