The term Open Source Software (OSS) has been around for a long time in the world of computer science. Open source software development is a process by which we can manufacture economical and qualitative software and its source could be re-use in the improvement of the software. The success of OSS relies on several factors, e.g. usability, functionality, market focus etc. But in the end how popular the software will be measured by the number of users downloading the software and how much the software is usable to the users. Open Source Software achieve the status for stability, security and functionality. Most of this software has been utilized by expert level users of IT. But from the general users or the non-computer user’s point of view the usability issues of Open source software has been faced the most criticism [25, 26, 27, 28, 29, and 30]. This factor i.e. the usability issues of general user is also responsible for the limited distribution of the open source software [24]. The development process should apply the “user-centered” methodology [25, 26, 27, 28, 29, and 30]. In this thesis paper the issues of usability in OSS development and how the usability of open source software can be improved will be discussed. Beside this I investigate the usability quality of free Open Source Linux-based operating system Ubuntu and try to find out the usability standards of this OSS.