A new model for determining maximum-efficiency inlet velocity in the gas-solid cyclone separator was developed analytically in this study. Previous maximum-efficiency inlet velocity (V-MEIV) models are derived at normal temperature and do not function properly under high-temperature conditions. The new model not only accounts for gas physical properties and cyclone structure dimensions, but also various particle characteristics as well as temperature; it can be applied to predict V-MEIV at both normal and high temperatures. Based on Yang's model, a hard sphere analogy of the soft sphere model was used to directly manage particle-wall collision as per the flow field of the cyclone. This model yields more accurate downward flow region width information than previously proposed models. If the radial displacement of a rebounded particle after collision is equal to the width of the downward flow region, then the corresponding inlet velocity is defined as the maximum-efficiency inlet velocity. Comparisons among different experimental results and other models' results indicate that the proposed model more accurately predicts maximum-efficiency inlet velocity. (C) 2019 Elsevier Ltd. All rights reserved.