The densities of both the vapor and liquid of 1-chloro-1,2,2,2-tetrafluoroethane along the phase boundary from 293 K to 395 K and in the liquid phase from 120 K to 268 K at pressures to 4.5 MPa have been measured. The measurements along the phase boundary curve were made with an apparatus that allows the simultaneous determination of liquid and vapor densities using Archimedes’ principle. The relative measurement uncertainties of the vapor pressure and the liquid and the vapor densities of R124 (mole fraction of impurities : less than 0.2%) at 373 K are +/-1 x 10(-4), +/-5 x 10(-4), and +/-1 x 10(-3), respectively. For the measurements in the liquid single-phase region along 11 quasi-isochores at pressures up to 4.5 MPa an isochoric apparatus was used. The relative measurement uncertainty of pv/(RT) is less than +/-1 x 10(-3) (95% confidence level). In addition, the vapor pressure in the temperature range from 120 K to 273 K was measured. Correlation equations are presented for reproducing the vapor pressures, liquid densities, and vapor densities. The results are compared with those of recent publications.