Cloud computing is a computing technique in which it allows resources being accessed in cloud without giving the burdens to the user's machine. An advantage of this approach is it can overcome the limitation of existing mobile phone technologies especially limited memory storage and limited processing power consumption. It will also increase the compatibility of the developed system with the mobile devices, thus, the usability of the system can be improved. In relation to that, this paper presents a comparative study of architectures for a usability-aware customized mobile learning management system (CMLMS). The study has been conducted to four mobile learning system architectures. The mechanism of the architectures, advantages and disadvantages have been determined using usability aspects as the main criteria of the comparison. Based on the conducted comparative study, cloud architecture for CMLMS has been chosen as the architecture to be implemented in the development of CMLMS. The study shows that the proposed architecture will give more benefits as compared to the studied architectures and some of the weaknesses of the studied architectures can be overcome. © 2012 IEEE.