3-Chloro-5-fluoroanisole is also referred to as 1-chloro-3-fluoro-5-methoxybenzene (IUPAC name). Two rotational isomeric forms, i. e. cis and trans forms of 3-chloro-5-fluoroanisole (1-chloro-3-fluoro-5-methoxybenzene) have been identified by ab initio and density functional theory (DFT) calculations.