This paper presents an overview of the development of online library catalogues, focusing on the third generation of catalogues. The purpose of this paper is to provide a brief overview of the development of online catalogues as well as to show models and other documents that have influenced their development. Throughout the past three decades, online library catalogues have undergone many changes that were mainly due to the rapid development of technology and the need to respond more readily to the potential demands of end users. In addition, the work outlines the main features of the Final Report of the Functional Requirements for Bibliographic Records (FRBR). The publication of this model marked the turning point in the development of online library catalogues. The focus is on the user and his needs. The model has made it easier to search and navigate within the catalog. The FRBR model brings four user tasks: to find the entity; to identify the entity; to select the entity and to obtain the entity. The user tasks are derived from the analysis of the entities as subjects of the user's interest, and the attributes that describe them, as well as the relationship between them. This work presents both theory analysis and a research part that is based on previously read literature. In its research, this paper presents two online library catalogues that feature third generation catalogues features and are used in libraries of the Republic of Croatia. Research is based on those two selected catalogues, as well as the FRBR user tasks. The aim was to demonstrate the successful implementation of the FRBR model in the Vero and Zaki catalogues through four user tasks.