This paper presents a lattice Boltzmann equation (LBE) model for simulating flows with multiple phases and components, focusing on one-component fluid systems that obey non-ideal gas equations of state and can undergo liquid-gas phase transitions. The model is momentum-conserving and can be made to correspond exactly to an isothermal process. The densities in bulk liquid and gas phases are derived as functions of a temperature-like parameter, and the density profile across the liquid-gas interface is shown to be isotropic. The surface tension, which can be varied independently, is calculated. The model is verified through numerical simulations. The LBE model is derived from the Lattice Gas Automaton (LGA) and offers computational efficiency and the ability to handle fluid systems with arbitrary numbers of components. It is free of the problems associated with LGA models, such as lack of Galilean invariance and velocity-dependent pressure. The model includes long-range interactions between particles, which are necessary for simulating non-ideal gases and their mixtures. The equation of state is exactly expressed in terms of the inter-particle potential and can be tuned to match any given functional form. When the equation of state is properly chosen, a liquid-gas phase transition can occur. The model is applied to one-component systems, and the equilibrium properties when a liquid-gas phase transition is allowed are discussed. The coexistence curve is calculated analytically from the microscopic mechanical balance condition, and the pressure tensor is given in analytical form. The density profile across the liquid-gas interface is obtained, and the surface tension is calculated as a function of the temperature-like parameter. The results are compared with thermodynamic predictions, showing that the LBE model corresponds to an isothermal PVT system when the inter-particle potential is chosen in a particular form. The model is verified by numerical simulations, and the agreement between the theory and the simulation is found to be excellent. The density profile is shown to be isotropic with respect to the underlying lattice structure. The surface tension is calculated and found to be independent of the density profile. The model is also used to simulate capillary waves and verify the Laplace law. The results show that the LBE model can accurately simulate liquid-gas phase transitions and other phenomena near the critical point. The model is efficient and can be applied to multi-component systems, although further research is needed to fully understand its capabilities. The major weakness of the model is the lack of an energy conservation relation and a dynamic temperature equation, although a static temperature can be identified with a particular choice of the effective mass.This paper presents a lattice Boltzmann equation (LBE) model for simulating flows with multiple phases and components, focusing on one-component fluid systems that obey non-ideal gas equations of state and can undergo liquid-gas phase transitions. The model is momentum-conserving and can be made to correspond exactly to an isothermal process. The densities in bulk liquid and gas phases are derived as functions of a temperature-like parameter, and the density profile across the liquid-gas interface is shown to be isotropic. The surface tension, which can be varied independently, is calculated. The model is verified through numerical simulations. The LBE model is derived from the Lattice Gas Automaton (LGA) and offers computational efficiency and the ability to handle fluid systems with arbitrary numbers of components. It is free of the problems associated with LGA models, such as lack of Galilean invariance and velocity-dependent pressure. The model includes long-range interactions between particles, which are necessary for simulating non-ideal gases and their mixtures. The equation of state is exactly expressed in terms of the inter-particle potential and can be tuned to match any given functional form. When the equation of state is properly chosen, a liquid-gas phase transition can occur. The model is applied to one-component systems, and the equilibrium properties when a liquid-gas phase transition is allowed are discussed. The coexistence curve is calculated analytically from the microscopic mechanical balance condition, and the pressure tensor is given in analytical form. The density profile across the liquid-gas interface is obtained, and the surface tension is calculated as a function of the temperature-like parameter. The results are compared with thermodynamic predictions, showing that the LBE model corresponds to an isothermal PVT system when the inter-particle potential is chosen in a particular form. The model is verified by numerical simulations, and the agreement between the theory and the simulation is found to be excellent. The density profile is shown to be isotropic with respect to the underlying lattice structure. The surface tension is calculated and found to be independent of the density profile. The model is also used to simulate capillary waves and verify the Laplace law. The results show that the LBE model can accurately simulate liquid-gas phase transitions and other phenomena near the critical point. The model is efficient and can be applied to multi-component systems, although further research is needed to fully understand its capabilities. The major weakness of the model is the lack of an energy conservation relation and a dynamic temperature equation, although a static temperature can be identified with a particular choice of the effective mass.