Tellurium dioxide is an ultra-wide bandgap semiconductor material playing a key role in optoelectronics. However, some of its physico-chemical properties such as the solid surface energy are still unknown. Indeed, the values available in the literature are scarce and contradictory. In this letter, the solid surface energy of tellurium dioxide (paratellurite) has been carefully determined to be 142±7 mJ/m2. This was achieved by measuring the static contact angles made by various liquids (deionized water, ethylene glycol, mercury and Galinstan) on top of a tellurium dioxide thin film, in a controlled environment.