This paper presents a procedure for the simultaneous prediction of fluid-fluid and solid-fluid equilibria of Light gases-heavy hydrocarbons systems under pressure. The fluid phases behaviour is described by the modified LCVM, an equation of state-G(E) model and the solid phase non-ideality is represented by the Wilson equation using the predictive local composition concept. This procedure was tested for several binary and ternary systems as well as multi-component systems leading to a good representation of both fluid-fluid and solid-fluid equilibria with a typical average absolute deviation of 1.5 K for the solid-fluid phase boundary of binary and ternary mixtures and of 0.5 K for multi-component systems. The AAD% in the fluid-fluid phase boundary of multi-component systems is of 3.2%.