Mobile learning (m-learning) is a learning tool in which it can be operated on mobile devices. Mobile System Analysis and Design (MOSAD) have been developed with the content of a topic from the System Analysis and Design (SAD) course conducted at Universiti Teknologi PETRONAS (UTP). This paper presents the results of usability study that has been conducted for MOSAD application. Two methods of usability test have been used; questionnaire and observation. Both methods have been chosen in order to get more reliable data of usability since both results will support each other. The usability questionnaire has been distributed to 66 students from SAD course whereas 12 of them were chosen to participate in usability observation. There are five usability factors involved in this usability test; consistency, learnability, flexibility, minimal action and minimal memory load. The usability questionnaire result shows that all tested usability factors have been given the score of 3.5 and above which is higher than Likert scale mean (2.5). Besides, the usability observation result has supported the result of usability questionnaire which indicates that the MOSAD application usability level is good and it can be a useful revision tool for the students of higher education. © 2011 Springer-Verlag.