The first paper of this study discussed the development of the Hu-Lee-Sum (HLS) correlation and demonstrated the generality and universality of the correlation to predict structure I hydrates suppression temperature for any single salt system. However, natural gas commonly forms structure II hydrates, and mixed salts naturally occur in oil and gas production. Therefore, reliable prediction of structure II hydrates suppression temperature in presence of mixed salts over a wide range of pressure is considerably important. The contribution for each salt in salt mixtures is accounted for in the effective mole fraction to extend the HLS correlation for mixed salts systems. Moreover, a parameter () is introduced to account for the effect of hydrate structure on the hydrate suppression temperature. Herein, the HLS correlation is further shown to be universal and reliable to predict the hydrate suppression temperature for more complicated systems for mixed gases and mixed salts. (c) 2018 American Institute of Chemical Engineers AIChE J, 64: 2240-2250, 2018