Reorientations of the CH3groups and of the cation are studied in the two phases (phase transition at 308 K) of (CH3)3NH+Cl-by quasielastic neutron scattering using a time of flight and a backscattering instrument. In the high temperature phase the experimental results can be described by rotational diffusion of the cation around its threefold axis withDr= 0·49 × 1012s-1(τc= 1/Dr= 2·05 ¢ 10-12s) at 333 K. The reorientation of the methyl groups is too slow to produce in this phase a quasielastic broadening detectable by the time of flight experiment. In the low temperature phase the observed spectra can be explained by simultaneous 120° jumps of the cation and of the methyl groups. The correlation times for the two reorientations are about the same: τc≈ 4 × 10-10s at 273 K.