Ionic liquids (ILs) have been proved to be excellently potential catalysts and solvents in a few chemical processes. In order to provide fundamental data for the reactor design and process optimization, it is essential to investigate the hydrodynamics and the mass transfer phenomena of liquid-solid twophase systems containing ILs. In this work, we focus on the investigation of the hydrodynamic properties of a spherical particle in ILs, and a series of experiments are implemented in a cylindrical bubble column with three different diameters of spherical particles made of borosilicate glass (2 mm, 3 mm and 4 mm) in three kinds of ILs ([Bmim][BE4], [Bmim][PF6] and [Bmim][Tf2N]). Moreover, Two key physical quantities (terminal velocity of particle and contact angle) are measured with a high-speed camera system and an automatic contact angle meter. Based on dimensional analysis, two novel empirical models of the drag coefficient (C-D) between a spherical particle and ILs are developed in the range of particle's Reynolds number (Re) from 0.1 to 85. The first model is simple and the calculated C-D agrees fairly well with the experimental data. Furthermore, in order to evaluate the effects of surface properties on C-D, a newly defined dimensionless number (Mo') is introduced into IL-particle flow studies for the first time, which comes into being a more rigorous model. The average predicted deviations of the two models are +/- 1.1% and +/- 1.5% respectively, which is much lower than that of contrastive models in the same situations (about 13.3% or more). These two models are significant for studying the hydrodynamics and mass transfer characteristics of IL-particle systems as well as the fluid dynamics simulation in related reactors. (C) 2019 Published by Elsevier Ltd.