In the present study, siderol acetate (1) was synthesized from siderol isolated from endemic Sideritis species, then its chemical structure was determined by using various spectroscopic methods (FT-IR, H-1 NMR, and C-13 NMR). The geometrical parameters, vibrational frequencies and gauge including atomic orbital (GIAO) H-1 and C-13 NMR chemical shift values for siderol acetate in the ground state have been calculated using the Density Functional Theory (DFT) and Hartree-Fock (HF) methods with the 6-31G(d) basis set. The calculated vibrational frequencies and H-1 and C-13 NMR chemical shifts have been compared with experimental values. A combined study based on NMR data and quantum-mechanical calculations using DFT/GIAO indicate that 1 is the correct structure of the title molecule.