Dynamics of guest molecules in kaolinite intercalation compounds with formamide (FA), formamide-N,N-d(2) (FA-d(2)), N-methylformamide (NMF), and N,N-dimethylformamide (DMF) has been investigated through H-2 NMR spectra and H-2 and C-13 spin-lattice relaxations. H-2 NMR spectra of kaolinite/FA-d(2) in the temperature range 200-350 K are composed of a narrow central peak, a resolved Fake doublet (RD1), and a distribution of Fake doublets (RDs). Quadrupole coupling constants and asymmetric factors obtained by fitting the spectral patterns indicate that RD1 is ascribed to the host hydroxyl group formed through H-D exchange during the synthesis and RDs to the guest molecules in the interlayer. Temperature dependence of the quadrupole coupling constant reveals that the guest molecules undergo librational motions and that the librational amplitude increases with temperature. Spin-lattice relaxations of H-1 and Si-29 spins are due to paramagnetic impurities. Si-29 spins relax through direct dipole-dipole interaction with electron spins, and spin diffusion plays a role in the H-1 relaxation. Variable-temperature C-13 spin-lattice relaxation times T-1 of kaolinite intercalates with FA, FA-d(2), NMF, and DMF were recorded at two magnetic fields. T-1 decreases with increasing temperature in all the samples and increases at the higher magnetic field in the order of FA > FA-d(2) > NMF > DMF, where it is almost independent of the field in kaolinite/DMF. C-13 spins relax through dipole-dipole interactions with H-1 and N-14 by the librational motions of the molecules. The field dependence indicates that the correlation times are of the order of nano-seconds, and that they are in the order of FA > FA-d(2) > NMF > DMF. The temperature dependence of the relaxation time is caused by the amplitude change of the librational motions. H-2 spins relax mainly through paramagnetic impurities being assisted by spin diffusion at low temperatures, and fluctuation of quadrupole interaction caused by the librational motions contributes to the relaxation at higher temperatures.