From the development of sour reserves and acid gas injection into oil reservoirs to the impact of hydrogen sulfide in CCS scheme, knowledge of the phase behaviour and thermophysical properties of the hydrogen sulfide + carbon dioxide is essential. Due to the toxicity of CO2 - H2S system, there are few experimental data available in the literature. The aim of this work is to investigate the densities and thermodynamic properties of acid gases and liquids. Densities of the 95.05 mol% CO2+4.95 mol% H2S binary system were measured continuously using a high temperature and pressure Vibrating Tube Densitometer (VTD), Anton Paar DMA 512 at pressures up to 41 MPa at five different temperatures, 273, 283, 298, 323 and 353 K in gas, liquid and supercritical regions. The specific heat capacity, compressibility factor, dew point and bubble point of the system have also been derived from the measured density data. The experimental data then were employed to evaluate the GERG-2008 equations of state and classical cubic equations of state (PR, SRK and VPT) with a CO2 volume correction model as well as volume translation. (C) 2016 Published by Elsevier B.V.