Four alkyl- and aryl(9-anthryl)carbinols (methyl, isopropyl, tert-butyl, and phenyl) were synthesized and revealed restricted rotation about the C9–C11 bond. Their free energy of activation for rotation has been determined, being 11.0, 14.0, 21.7, and 9.8 kcal/mol, respectively. The application of NOE enhancement and relaxation time measurements for the determination of the activation energy for bond rotation is described. The good agreement with the values obtained with the coalescence temperature method bears out that the NOE based approach is a good alternative for the determination of high rotational barriers. Molecular Mechanics (MM2) calculations give values close to the experimental ones. © 1995, American Chemical Society. All rights reserved.