Metal organic frameworks have been recently highlighted as promising materials for heterogeneous catalysts. In this study, MIL-101, a chromium-based metal organic framework was synthesized using the solvothermal method and functionalized through sulphation. The catalytic activities of MIL-101 and sulphated MIL-101 (MIL-101s) were tested in the esterification of acetic acid. The conversion of acetic acid increased from 73.7 to 86.2 % after sulphation at 363K. These results prove that the sulphation of MIL-101 is an effective way to enhance the acidity and catalytic activity of MIL-101. The characterization of MIL-101 and MIL-101s was performed using FTIR, BET, XRD, TG-DTA, SEM/EDX, XPS, and potentiometric titration methods. A BET analysis showed that MIL-101 maintained its porosity after sulphation. The sulphation reduced the surface area and pore volume but increased the acidity.