Abstract 2-(4-Chlorophenyliminomethyl)-8-hydroxyquinoline was synthesized and crystal data was obtained in the orthorhombic space group P-1, with Z = 4. Unit cell parameters a = 4.744(7) Å, b = 9.981(15) Å, c = 27.27(4) Å and V = 12915(3) Å 3. In this paper the structural properties and vibrational frequencies of 8-hydroxyquinoline derivative, 2CP8HQ, are studied with the B3LYP and HF methods. Two stable conformers are obtained. The calculated frequencies are in good agreement with the experiment results. It is indicated that both of theoretical calculations were suitable for molecular vibrational frequencies study and the scaled B3LYP method was superior to the scaled HF methods.