A built experimental set-up was employed for the estimation of the solid-liquid equilibria of alternative refrigerants systems. The behavior of two binaries, i.e. carbon dioxide + 2,3,3,3-tetrafluoroprop-1-ene (CO2 + R1234yf) and carbon dioxide + 1,3,3,3-tetrafluoropropene (CO2 + R1234ze(E)), was measured down to temperatures of 122.6 K. The triple points of the pure fluids constituent the binary systems were measured, together with the triple points of the two mixtures with varying their composition. The results obtained for the mixtures were interpreted by means of the Schroder equation. (C) 2013 Elsevier B.V. All rights reserved.