The vapor pressure of 2,3,3,3-tetrafluoropropene (HFO-1234yf) was measured at temperatures from (248.17 to 361.05) K with pressures from (123.1 to 2955.2) kPa, together with the vapor pressure of 2-chloro-1,1,1,2-tetrafluoropropane (HCFC-244bb) at temperatures among (268.19 to 349.07) K with pressures from (49.7 to 645.9) kPa. The uncertainties of the measurements for temperature and pressure were within 20 mK and 1.5 kPa, respectively. The experimental vapor pressures of HFO-1234yf were correlated with the Wagner type equation, and vapor pressures of HCFC-244bb were correlated with the Antoine type equation.