This paper deals with the determination of recommended temperature dependent NRTL parameters by simultaneous correlation of VLE-,gamma(infinity)-, and h(E) data from the Dortmund Data Bank (DDB) using an interactive program package. Correlation results for selected mixtures are discussed in detail. The program package RECVAL is directly interfaced to the Dortmund Data Bank, makes extensive use of graphics for data representation and may be extended for the correlation and prediction of further mixture or pure component data. To ensure rapid conversion in case of a large amount of data, simultaneous convergence of the outer parameter fitting loop and the inner phase equilibrium iterations is employed. Recommended temperature dependent NRTL parameters have been determined for 133 binary systems. These parameters have been obtained by a simultaneous fit to VLE-, gamma(infinity)-, and h(E)-data stored in DDB.