The vapor pressures of 1,1,1-trifluoroethane (HFC-143a) and 1, 1, 1,3,3,3-hexafluoropropane (HFC-236fa) were measured with a modified Burnett apparatus. The vapor pressures were measured at temperatures from 251 to 343 K and pressures from 292 to 3553 kPa for HFC-143a, and at temperatures from 253 to 396 K and pressures from 43 to 3064 kPa for HFC-236fa. The measurement uncertainties were estimated to be within +/- 10 mK and +/- 1.2 kPa. Two vapor pressure equations were developed to represent the experimental data for HFC-143a and HFC-236fa, respectively. The results were also compared with available literature data. (c) 2004 Elsevier B.V. All rights reserved.