Thermal management of electronic units is one of the major concerns in the modern scenario which demands to be solved efficiently and reliably. Miniature loop heat pipes (MLHPs) are one the promising solution to this problem and are expected to remove high heat flux effectively. MLHPs are passive two-phase heat transfer devices, which rely on the capillary mechanism for pumping working fluid. The enhancement of thermal performance and optimization of design demands the improvement of the theoretical modelling capabilities of MLHPs. In this work, a one-dimensional steady-state mathematical model of MLHP is developed to predict the operating evaporator temperature for a given heat load and sink temperature. The annular flow model is adopted in the condensing tube for computing the two-phase flow within the MLHP. The current simplified model can predict the operating temperature, thermal resistance, heat leak and the varying two-phase length. The model is validated with the experimental data available in the literature and a good agreement is obtained between the model predictions and experimental data. Parametric studies are conducted to investigate the effect of varying heat load, sink temperature and geometrical configuration on the operating evaporator temperature. The performance of the MLHP increases as the vapor line diameter increases because of the reduction of the vapor pressure drop. The optimum diameter and length of vapor line was found to be 5 mm & 100 mm respectively. The current model is simple in formulation, which can be used to optimize the design and can help in a better understanding of the device.