2,3,3,3-Tetrafluoroprop-1-ene (R1234yf) and trans-1,3,3,3-tetrafluoropropene (R1234ze(E)) are fluorinated hydrocarbon that has been recently proposed to replace R134a in automotive air-conditioning and other applications. In this work, the densities of 2,3,3,3-tetrafluoroprop-1-ene (R1234yf) and trans-1,3,3,3-tetrafluoropropene (R1234ze(E)) were measured in compressed liquid region, using a vibrating tube densimeter. A total of 128 experimental data for R1234yf and 131 experimental data for R1234ze(E) along nine isotherms between (283 and 363) K with pressures up to 100 MPa were obtained. The uncertainty for each measurement was estimated, and the maximum expanded uncertainty with a level of confidence of 0.95 (k = 2) of R1234yf and R1234ze(E) are 0.33% and 0.23%, respectively. (C) 2013 Elsevier Ltd. All rights reserved.