The molecular conformation and mobility of the intercalated surfactant molecules cetyltrimethylammonium bromide (CTMAB) have been studied using Fourier transform infrared spectroscopy (FTIR) and high-resolution single-pulse C-13 magic angle spinning nuclear magnetic resonance (C-13 SP MAS NMR) spectroscopy. The conformation and mobility of alkyl chains were found to be a function of the surfactant concentration. The splitting of the methylene scissoring mode at 1473-1463 cm(-1) and the rocking mode at 730-720 cm-1 in FTIR are considered to be diagnostic of the packing density increase of the intercalated surfactants within the clay gallery. Compared with the C-13 Sp MAS NMR spectrum of CTMAB in the bulk state, 1-3 ppm upfield chemical shifts for end-methyl (δ C-16) and methylene (δ C-15, δ C2-14) of the intercalated surfactant molecules in the hybrids indicate a freer conformational situation. For these hybrids, the conformational freedom decreases with increased of surfactant concentration. In addition, on ∼ 2 ppm downfield shift for the C-1 carbon atom in the hybrids with higher surfactant content suggests a special local environment. This study demonstrates the different mobility of carbon atoms in the intercalated alkyl chain. © 2005 Elsevier Inc. All rights reserved.