In order to determine the stereospecificity of the Thermal cyclization of [(E)-2,2-dimethyl-5-phenyl-4- hexenyl] hydroxylamine (1), the relative configuration of the title compound, C₁₄H₂₁ NO, (2), has been established by single-crystal X-ray diffraction. The pyrrolidine ring adopts an envelope conformation with the N atom out of the ring plane. The molecules form hydrogen-bonded pairs through a centre of inversion [O...N 2.808 (5) A, and O---H...N 160 (4) °].