There is no heat transfer correlation available in the Inverted Slug Film Boiling (ISFB) regime. In this study, a new correlation for film boiling in a vertical channel is proposed using a semi-empirical model. This correlation is applicable in the Inverted Annular Film Boiling (IAFB) heat transfer regime as well as ISFB heat transfer regime. A semi-empirical model is developed to establish the functional dependence of the Nusselt number on various controlling parameters. Test data obtained from the transient reflood tests carried out in a full length 7 x 7 vertical Rod Bundle Heat Transfer (RBHT) facility are used to develop the correlation. The predicted Nusselt number agrees within 15% with the RBHT data set and other data set available in the literature. This heat transfer correlation is applicable up to a void fraction of 90%, i.e., both in the IAFB and ISFB regimes. The proposed correlation is also applicable to a tube geometry using a modified coefficient in the correlation with an error less than 10%. (C) 2016 Elsevier Ltd. All rights reserved.