Geometric parameters and FT-IR spectrum of 6-bromo-8-thia-1,4-epoxybicyclo[ 4.3.0]non-2-ene were computed by the HF, B3LYP, B3PW91 and mPW1PW91 methods in conjunction with the 6-31G(d,p) basis set. The calculated IR spectra are in a good agreement with the observed FT-IR spectrum. A general better performance of B3LYP, B3PW91 and mPW1PW91 versus HF was quantitatively characterized by using PAVF 1.0 program. Optimal uniform scaling factors calculated for the title compound are 0.8952, 0.9552, 0.9520 and 0.9456 for HF, B3LYP, B3PW91 and MPW1PW91 methods, respectively.