Geometry optimization of methanol monomer and trimer in vacuum, as well as in methanol and argon environments, was performed using methods of quantum-chemical simulation (DFT, B3LYP/cc-pVTZ level of theory). It is shown that the influence of the argon or methanol environment on the structure of methanol molecules presents as an increase in the length of C – H and O – H bonds. The calculated frequencies of IR absorption bands for three different environments show that the effect of the environment is manifested as a red shift of the corresponding spectral bands. Moreover, the argon environment has a stronger effect on the structure and vibrational spectra of methanol clusters than the methanol environment.