Mobile assessment is a new delivery mode of assessment that offers ubiquitous access to testing material anytime and anyplace. Due to its mobile features, it has the potential to complement and to improve other assessment delivery modes (paper-and-pencil based or computer-based). Moreover, semantic Web technologies have been applied in recent years with different purposes in education. But, their applications for generating useful personalized mobile assessment resources have not been researched enough so far. In this paper, we propose an assessment system built on semantic Web technologies and Web services to support personalized self-assessment in mobile environments. In particular, we present the MobiSWAP system that presents an assessment tool based on the use of ontologies and the REST architecture. With MobiSWAP learner can generate and answer to questions and tests using mobile devices. We provide the system architecture and the implementation. We have carried out also an experiment with computer science students to determine the degree of their satisfaction to use the MobiSWAP system and to adopt mobile assessment.