The rotational structure of the pseudorotational (PR) band n=0-->n=2 has been observed in jet-cooled tetrahydrofuran in the 170-360 GHz frequency range. The observed transitions were analyzed together with the previously obtained microwave data of Meyer and co-workers [R. Meyer, J. C. Lopes, J. L. Alonso, S. Melandri, P. G. Favero, and W. Caminati, J. Chem. Phys. 111, 7871 (1999)]. The experimentally observed transitions provide direct spectroscopic evidence of the symmetry ordering of the lowest four observed PR states. Based on the symmetry properties of the pseudorotational states involved in this study, an analytical model of the potential energy surface (PES) along the pseudorotational path has been proposed that provides a consistent explanation of all the observed transition frequencies, including those from the early IR work. In addition, an analysis of the variation of the rotational constants of the molecule in different PR states has been performed using the proposed model. This analytical PES and the derived rotational constants are compared to the results of it ab initio calculations. A discussion of the results obtained by different methods is given. (C) 2003 American Institute of Physics.