The viscosity of polydimethylsiloxane {(CH3)(3)SiO[SiO(CH3)(2)](n)Si(CH3)(3) with CAS# 63148-62-9} and 1-propene,1,1,2,3,3,3-hexafluoro-, oxidized,polymd {CF3O[CF2C(CF3)FO](n)(CF2O)(m)CF3 with CAS# 69991-67-9} has been measured with an oscillating sinker viscometer at temperatures between (313 and 373) K and a pressure of 0.1 MPa. The viscometer was calibrated with a reference fluid and found accurate to +/- 2%. The viscosity reported for 1-propene, 1, 1,2,3,3,3-hexafluoro-, oxidized,polymd at T = 373 K is 5% above the value reported by the supplier and these differences increase smoothly with decreasing temperature to be about 15% at T = 333 K. The density of both fluids has been determined with a vibrating tube densimeter at temperatures in the range (313 to 363) K at a pressure of 0.1 MPa with an uncertainty of +/- 0.03% and our results are less than 0.5% above the values reported by the suppliers in the overlapping temperature range. (c) 2005 Elsevier Ltd. All rights reserved.