The spectral characteristics of thiamine hydrochloride in the absence and presence ofβ–-cyclodextrin (β–-CD) have been investigated to reveal the nature of the non covalent interaction of the cyclodextrin system. It is indicated that Fourier transform infrared (FTIR) spectrometry could provide a unique and sensitive technique for the detection of microenvironment changes in solutions of the guest, which is especially important in the cases like the weak interaction between thiamine hydrochloride andβ–-CD, where other spectroscopic data lack of distinct changes.