Project “mPOLONA” (hereinafter: Project) consists of extending, improving the functionality and maturity of the existing service, the Polona digital library. It is the largest portal of its kind in Poland, developed by the National Library (hereinafter: (BN) since 2006. It makes available digitised collections of BN (more than 3 250 000 objects), the Jagiellonian Library and other cultural institutions, gathered in the Digital Repository BN (hereinafter referred to as: RCBN). The project includes designing, creating and implementing an application dedicated to existing and new users interested in using Polona on mobile devices (this interest is confirmed by numerous messages from users in this matter). Based on the Polony API (application development interface) and a number of open source solutions, including a collection of tools for the presentation of digital images IIIF (International Image Interoperability Framework), a program will be created to reflect and expand the functionality of the standard Polona web application, adapted to devices with a touch screen. In order to optimise work on other types of devices, a new interface will be developed as well as mechanisms for adjusting the viewed content to the device, e.g. through automated image framing. However, the application is designed to maintain full compatibility, visual and functional consistency with the home service, so as not to interfere with the sense of working with the same service for people using both versions of Polona. The application created in the Project will be available for the most popular mobile operating systems iOS and Android. Polona’s mobile application will enable all users to browse, search, share and download publicly available Polona resources, which constitute a specific type of Public Sector Information (hereinafter: ISP).