Abstract-Context-aware mobile applications can adapt to di�erent mobile, user and application contexts. Mobile cloud computing has been integrated with those applications to exploit the relatively infinite cloud resources. This paper proposes a context-aware cloud-based MObile application for assessment and training of visual Cognitive Abilities (MOCA). Those abilities, such as the visualization ability of recognizing rotated objects, constitute an integral part of student intelligence. The need to ubiquitously and continuously deliver exercises relevant to a speci!c visual cognitive ability or skill according to the student pro!ciency and context has stimulated proposing MOCA. Integrating cloud computing with MOCA allows creating an extendible repository on the cloud such that the visual material does not affect and is not affected by the relatively limited mobile resources. In MOCA, we propose a hierarchical data structure suitable for the assessment of the various cognitive abilities and skills in terms of related ones. MOCA is also a framework for building applications based on visual cognitive abilities, such as teaching visual science concepts and the visual classi!cation and diagnosis of medical images, and possibly training and assessment systems for other types of cognitive abilities. Two prototype mobile applications have been developed based on MOCA for the visualization ability and for visual classi!cation of science concepts. Empirical evaluation has shown the effectiveness of MOCA in training the students and the satisfaction of the students and teachers with its capabilities.