In this work IR, Raman and optical properties of three conformers (Chair, Boat and Stirrup) of hydrogenated BN (BHNH) sheet are presented in detail. The blue shift of Raman peak corresponding to the B-N vibrational mode (E-2g) within h-BN layers can be attributed to shrinkage of lattice parameter. The phonon dispersion and density of phonon states are studied in depth to explore the nature of vibrational bonding in the three conformers of BHNH sheet. Vibrational study reveals that all the three conformers are very much stable. The dielectric and absorption spectra are different for Chair, Boat and Stirrup conformer and also compared with h-BN sheet. The estimated results indicate that IR spectra and Raman shift can be a useful technique to investigate the formation of BHNH sheet and to make a distinction between the three conformers. (C) 2013 Elsevier B. V. All rights reserved.