This paper presents liquid liquid equilibria and densities of the coexisting phases for the system water-methanol-dichloromethane in the temperature range between 20 and 90 °C. 63 connodes, structured in isothermal datasets, have been measured. For each of the isothermal datasets a regression with the UNIQUAC as well as the NRTL model has been made. Both models describe the data within the experimental error. Simultaneous fit of all datas leads to unacceptable high deviations from experimental values for both the UNIQUAC and the NRTL modell. The extension of the UNIQUAC equation with a two parameter hyperbolic temperature function for the interaction parameters yields significantly better results as the original equation when applied to the fit of all available data.