This paper investigates the use of infinite-dilution activity coefficients to define the interaction parameters of the Redlich-Kwong equation of state (SRK-EOS), with the Huron-Vidal mixing rules. The group-contributions of a UNIFAC-type model were regressed from experimental infinite-dilution activity coefficients of a number of significant systems, including strongly polar components. Such parameters were then used to predict vapor-liquid equilibria (VLE) over the whole composition range, at pressures up to 6 MPa, with generally good results.