Purpose - The aim of the research was to design and evaluate a prototype electronic performance support system (EPSS) for libraries. Design/methodology/approach - Based on the theory of performance support and usability problems identified in the use of academic libraries, a performance support system for using the Dewey Decimal Coding system was designed, implemented and evaluated. The system embedded two components: a tutorial to develop knowledge and two games to develop skills. An experimental evaluation was conducted with three groups of students to assess the effects of the two components. Findings - The study found that students found the system useful. There was a large difference in confidence in own knowledge (in favour of the groups who studied the tutorial component), approaching statistical significance. Although no major usability problems were identified, some specific problems surfaced that should be addressed in future work. Results from staff (who also used the system) confirmed the findings from students and also highlighted the scaffolding function of the EPSS. Research limitations/implications - This research has shown the viability of performance support for academic libraries. However, it identified issues for future research, including the inclusion of sound and speech, dynamic adaptability of content to make the system more suited to specific libraries and academic disciplines, and integration with existing library systems and virtual learning environments. Originality/value - The study has extended the concept of performance support to the domain of academic libraries. Given its wide applicability, the system should be valuable to academics and students worldwide.