Cross-polarization,13C rotating frame spin-lattice relaxation and C laboratory frame spin-lattice relaxation processes have been studied for different cellulose samples by CP/MAS13C NMR spectroscopy. It was found that the CP process can be described by a simple thermodynamic model and relative intensities of the respective resonance lines are consistent with the atomic ratios for the spectra obtained at a contact time of about 1 ms. The observed rotating frame spin-lattice relaxation times TC10were dominantly dependent on the time constant TDCHby which13C nuclei were coupled to the1H dipolar spin system. It was, therefore, impossible to obtain information about molecular