FT-IR and Raman spectra together with the vibrational spectral assignments between 4000 and 400 cm(-1) of 4-(1-Pyrrolidinyl)piperidine (4-pypp) have been reported. The optimized structural parameters (bond lengths. bond and dihedral angles), normal mode frequencies and corresponding vibrational assignments of 4-pypp (C(9)H(18)N(2)) have been theoretically examined by means of B3LYP density functional method with 6-31G(d) basis set. Infrared intensity and Raman activities have also been calculated and reported. Theoretical results have been successfully compared against obtained experimental data. (C) 2009 Elsevier B.V. All rights reserved.