Ab initio and density functional theory methods are applied to investigate the molecular structures, intramolecular orbital interactions, and F-19 and Se-77 NMR chemical shifts of o-selenobenzyl fluoride derivatives, ArSeX (Ar = C6H4CH2F; X = CN, Cl, Me), at both RHF and B3LYP levels with the basis sets 6-311G** and 6-311+G**. There are two stable rotational conformers for ArSeX. The energy differences between both conformers for each compound are small (within 2 kcal/mol) at various levels.