Solid-fluid equilibria (SFE) in natural gas systems were calculated using a number of equations of state (EOS) including the Redlich-Kwong-Soave (RKS) equation, the Peng-Robinson (PR) equation, the Patel-Teja (PT) equation, and a Lennard-Jones (LJ) equation of state. A number of mixing rules were used with one of the equations of state to study the effect of the mixture model on calculations of SFE. The natural gas systems studied included n-alkanes in supercritical carbon dioxide and n-alkanes in ethane. The predictive capabilities of the equations were examined by extrapolation to high pressures and temperatures where the extrapolated results were compared with experimental results. (C) 1998 Elsevier Science B.V. All rights reserved.