The ion exchange membrane (IEM) is a key component that helps achieve good performance in membrane capacitive deionization (MCDI). However, systematic researches have been limitedly conducted regarding the effect of IEM characteristics on MCDI performance. The aim of this study is to investigate the effects of the characteristics of the cation exchange membrane (CEM) on MCDI performance. Salt adsorption capacity (SAC), maximum average deionization rate (MADR), and charge efficiency were chosen to demonstrate MCDI performances. Only MADR was significantly affected by CEM characteristics. Additionally, MADR showed a positive relationship with the transport number divided by total electrical resistance (R-2 = 0.83). Therefore, CEM should have a high transport number and low electrical resistance for fast rate-capable MCDI. The correlations between CEM characteristics and MCDI performances revealed through this study are expected to further develop high-performance MCDI.