The diffusion coefficients of dimethyl sulfoxide, dimethyl sulfone, N-15-labeled DNO3, and O-17-labeled D2O in solutions of 0.6-0.8 weight fraction D2SO4 in D2O 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 D2SO4 in D2O at temperatures from 248 to 298 K is also reported.