Experimental data on the pressure-density-temperature and air-liquid interfacial tension-temperature relations are reported for two fluorinated substances that meet the present requirements of the technological materials and working media for thermodynamic cycles to have zero ozone depletion potential (ODP) and limited global warming potential (GWP). The data for 1,1,1,3,3-pentafluorobutane (HFC-365mfc) and 1,1,1,2,2,3,3-heptafluoro-3-methoxy-propane (HFE-347mcc, HFE-7000) were obtained with a constant volume apparatus at temperatures from (208 to 353) K and at pressures from (1 to 40) MPa. Thus, the temperature-pressure region covered with experimental p-rho-T data has been substantially extended for both substances. The combined uncertainty at the 0.95 confidence level of the reported density data takes its maximum value at the lower end of the temperature interval, namely 1.0 kg.m(-3) (0.75.10(-3)rho) for HFC-365mfc and 1.5 kg.m(-3) (10(-3)rho) for HFE-347mcc. The root-mean-square deviation of the reported data from the Helmholtz free energy equation of state fitted to them is 0.38 kg.m(-3) (4.10(-4)rho) for HFC-365mfc and 0.17 kg.m(-3) (1.2.10(-4)rho) for HFE-347mcc. In addition, experimental 0.1 MPa density data and air-liquid surface tension data are reported for both substances obtained with the buoyancy method and the Wilhelmy plate method, respectively, at temperatures from (262 to 307) K.