AbstractPulsed NMR studies to measureT1of35Cl and19F for a sample of neat ClO3F over the entire liquid range (130 to 368 K) were carried out. The chlorine nucleus is relaxed entirely by the quadrupole interaction and sincee2qQ for25Cl is known it is possible to determine experimentally the correlation time for molecular orientation τ0,2. The fluorine relaxation is dominated by the spin‐rotation interaction. WithT1data for19F and an independent knowledge of the effective spin‐rotation constant, the angular momentum correlation time τJcan be determined experimentally. The results for this quasi spherical model are in accord with rotational diffusion theory and Hubbard's relation. τΘ,2τJ= 1/6k T, at temperatures near the melting point and they agree over the entire liquid range with the extended treatment of