All available thermodynamic and phase diagram data for the condensed phases of the ternary reciprocal system (NaF + SiF4 + Na2O + SiO2) have been critically assessed. Model parameters for the unary (SiF4), the binary systems and the ternary reciprocal system have been found, which permit to reproduce the most reliable experimental data. The Modified Quasichemical Model in the Quadruplet Approximation was used for the oxyfluoride liquid solution, which exhibits strong first-nearest-neighbor and second-nearest-neighbor short-range ordering. This thermodynamic model takes into account both types of short-range ordering as well as the coupling between them. Model parameters have been estimated for the hypothetical high-temperature liquid SiF4. (C) 2011 Elsevier Ltd. All rights reserved.