In this work, the prediction of hydrate formation conditions in the presence of the thermodynamic inhibitors is presented. Using the van der Waals-Platteeuw model, computation of the L-S-G equilibrium is carried out for hydrate formation conditions in the presence of methanol and electrolytes using the local composition models of the UNIQUAC-NRF and Electrolyte-UNIQUAC-NRF for nonelectrolyte and electrolyte systems, respectively. The model is applied to calculate water activity coefficient for prediction of the hydrate formation pressure of methane, ethane, H2S in the absence and presence of the electrolytes. The results of the present model are compared with the experiment and UNIFAC group contribution model. Also both UNIQUAC-NRF and UNIFAC activity coefficient models are used to predict the hydrate formation conditions in the presence of alcohols. The results show very good agreement with the experiment. (C) 2013 Elsevier B.V. All rights reserved.