The aim of this chapter is to report the study of a novel liquid-vapour separatorincorporated gravity-assisted loop heat pipe (GALHP). This involves a dedicated conceptual formation, thermo-fluid analyses, and computer modelling and experimental validation. The innovative feature of the new GALHP is the integration of a dedicated liquid vapour separator on top of the evaporator section, eliminating the potential entrainment between the heat pipe liquid and the steam stream, while addressing the inherent 'dry-out' problem exhibited in the traditional GALHP. Based on this recognised novelty, a dedicated steady-state thermal model covering the mass continuity, energy conservation and Darcy equations were established. Under the specifically defined operational condition, the proposed GALHP has more evenly distributed axial temperature profile. The effective thermal conductivity in the proposed GALHP was 29,968 W/C m. It is therefore concluded that the novel heat pipe could achieve a significantly enhanced heat transport effect. The results derived from this research enabled characterisation of the thermal performance of the proposed GALHP and validation of the developed computer simulation model. The research will enable design, optimisation and analysis of such a new GALHP, thus promoting its wide application and achieving efficient thermal management.