In this work, optimized molecular structure, vibrational frequencies and corresponding vibrational assignments, HOMO-LUMO energy values and electron density clouds of 3-hydroxyphenylboronic acid have been calculated by ab initio Hatree-Fock (HF) and density functional theory methods. The compound has eight conformers depending on the directions of hydrogen atoms bonded to oxygen. The computational results have diagnosed the most stable conformer of the compound as cis-trans (ctt) form. The calculated frequencies and optimized geometry parameters (bond lengths and bond angles) for the most stable conformer are in a good agreement with the corresponding experimental data.