Online Public Library Catalogues (OPACs) are widely used electronic library catalogues giving a wealth of remote access to library information resources. Users should be involved early in the OPAC development cycle process in order to ensure a usable and functional interface, as the integration of user-defined requirements of OPACs, along with the other Human-Computer Interaction considerations, offer a better understanding of user perceptions and expectations respect of OPACs, ultimately resulting in truly user-centred OPACs. Accordingly, the purpose of this study was to establish user suggestions for a typical OPAC application's functionality and features. To this end, an experiment was undertaken to find out the type of interaction features that users prefer to have in an OPAC. The study revealed that regardless of users' Information Technology (IT) backgrounds, their functionality expectations of OPACs are the same as users are expecting OPACs to facilitate easier ways to achieve their tasks. However, based on users' previous experiences with OPACs, their requirements with respect to specific features may change.