The diffusion coefficients of dimethyl sulfoxide, dimethyl sulfone, 15 N-labeled DNO 3 , and 17 O-labeled D 2 O in solutions of 0.6-0.8 weight fraction D 2 SO 4 in D 2 O were studied at temperatures from 248 to 298 K by the pulsed gradient spin-echo NMR technique. Diffusion coefficients for these compounds are reported, and an empirical technique for extrapolating the results to sulfuric acid of stratospheric compositions and temperatures is discussed. The viscosity of 0.7 weight fraction D 2 SO 4 in D 2 O at temperatures from 248 to 298 K is also reported.