The inter-phase slip plays an important role in simulating the condensing flow, which is, however, generally neglected in most numerical studies. To address this, a generalized multi-fluid model is newly developed to predict the two-phase condensing flow in the presence of a carrier gas, where both the inter-phase velocity slip and the temperature difference are taken into account. The multi-fluid model is performed to simulate the condensing flow in two types of supersonic nozzles. Also, the traditional noslip model is employed for comparing with the multi-fluid model. The simulated results obtained from the multi-fluid model are found to agree better with the experimental data. The effects of the inter-phase slip are revealed qualitatively by comparing the results obtained from these two models. The results show that the effects of inter-phase slip should not be neglected in the whole condensation process. At the initial stage of condensation, both the inter-phase velocity slip and temperature difference are noteworthy. When the condensation finishes and the gas liquid equilibrium achieves, the inter-phase velocity slip and temperature difference become slight and can be neglected. Crown Copyright (C) 2013 Published by Elsevier Ltd. All rights reserved.