Benzyl isothiocyanate (BITC) and phenylethyl isothiocyanate (PEITC) are two poorly water-soluble plant components that can form inclusion complexes with beta-cyclodextrin (beta-CD), namely, beta-cyclodextrin-BITC and beta-cyclodextrin-PEITC, that are two water-soluble complexes. The inclusion complexes were prepared by two independent processes: physical mixing and coprecipitation. The content of guest molecules in the complexes was measured by UV spectrophotometry. Response surface design (RSD) was applied to optimize the preparation conditions of said complexes. The results showed that the embedding ratios for beta-CD-BITC and beta-CD-PEITC were 94.9% and 94.1%, respectively. Variance analysis revealed that the mass ratio and the inclusion temperature were two important factors in terms of inclusion action. The optimum conditions for the inclusion of beta-CD-BITC were a mass ratio of 0.17 and an inclusion temperature of 57.99 degrees C, and those for beta-CD-PEITC were a mass ratio of 0.0057 and an inclusion temperature of 64.87 degrees C. The inclusion complexes prepared were qualified by thermal methods [thermogravimetry (TG) and differential scanning calorimetry (DSC)], Fourier transform infrared (FTIR) spectroscopy, and X-ray powder diffraction (XRD). The thermal analysis of beta-CD and the two complexes indicated that an interaction between the guest and host molecules did occur. BITC and PEITC could be partially embedded in the hydrophobic cavity of beta-CD, so the formation of the said complexes was established. The X-ray and FTIR results support this indication of inclusion behavior.