 The following list summarizes fields of his scientific work but is in no way complete.liquid-liquid equilibria, solid–liquid equilibria, gas solubilities, heats of mixing, activity coefficients and more)

Gmehling began in the 1970s with the systematic evaluation of the scientific literature, aiming to build a data bank for vapor-liquid equilibria.These data were needed for the development of a new method for the prediction of activity coefficients named UNIFAC.