A highly accurate P,V,T,x model is developed for aqueous chloride solutions of the binary systems, viz. (LiCl + H2O), (NaCl + H2O), (KCl + H2O), (MgCl2 + H2O), (CaCl2 + H2O), (SrCl2 + H2O), and (BaCl2 + H2O). The applied ranges of temperature, pressure, and concentrations for the systems (LiCl + H2O), (NaCl + H2O), (KCl + H2O), (MgCl2 + H2O), (CaCl2 + H2O), (SrCl2 + H2O), and (BaCl2 + H2O) are (273 K to 564 K, 0.1 MPa to 40 MPa, and 0 to 10 molal), (273 K to 573 K. 0.1 MPa to 100 MPa, and 0 to 6.0 molal), (273 K to 543 K, 0.1 MPa to 50 MPa, and 0 to 4.5 molal), (273 K to 543 K, 0.1 MPa to 40 MPa, and 0 to 3.0 molal), 1:273 K to 523 K, 0.1 MPa to 60 MPa, and 0 to 6.0 molal), (298 K to 473 K, 0.1 MPa to 2 MPa, and 0 to 2.0 molal) and (273 K to 473 K, 0.1 MPa to 20 MPa, and 0 to 1.6 molal), respectively. Comparison of the model with thousands of experimental data points concludes that the average deviation over the above T,P,m range is 0.020% to 0.066% in density (or volume) for these systems, which indicates high accuracy. From this model, various volumetric properties, such as the apparent molar volume at infinite dilution and isochores of fluid inclusions, can be calculated, thus having a wide range of geological applications, such as reservoir fluid flow simulation and fluid-inclusion study. A computer code is developed for this model and can be downloaded from the website: www.geochem-model.org/programs.htm and online calculations is made available on: www.geochem-model.org/models.htm (C) 2008 Elsevier Ltd. All rights reserved.