Technology development has left a major impact on the development of library catalogs and their use. Today's users from the library catalog expect easy access and interface that mimics modern internet search engines. These changes have also affected user behavior while browsing the catalog. This master thesis deals with the study of the latest generation catalog and user interactions while using the catalog. In the theory part of the paper, a historical overview of the development of library catalogs is given, also functionality of discovery tools and the methods for researching library catalogs are presented. The purpose of this thesis is to study the integrated library catalog of Linnaeus University Library, which functions and search capabilities can be found within the Primo integrated library system. The paper also explores user behavior and opinions about browsing the mentioned library system. The paper explores the functioning of the library catalog as a unique access point for searching information and sources available in the library. As a research instrument, a catalog of the Linnaeus University Library in Sweden was selected, more precisely their OneSearch search interface. The aim of this master thesis is to analyze OneSearch interface and to observe library users while they are searching the catalog. For the purposes of this thesis three methods of research, analysis of the library catalog, methods of observation and a semi-structured interview were selected. The research conducted has shown the problems users face when searching for the catalog with one access point. Work indicates the problem of ranking the results by relevance within the catalog and shows that search options within the catalog itself are unused. The research also shows the user experience and opinions about using the OneSearch interface as an information access tool.