Purpose Considering the shortcomings of the ASIS&T Web-based thesaurus in representing concepts and semantic relations, there is a need to use more effective semantic tools, such as ontologies. The purpose of this paper is to build a prototype ontology (ASIS&TOnto) based on a Web-based thesaurus. Design/methodology/approach The prototype ontology was built based on the ASIS&T Web-based thesaurus by using the methodology developed by Noy and McGuinness (2001) and with the use of Protégé 4.3.3. With regard to the purpose of the study and the massive amount of concepts represented in the ASIS&T thesaurus, the focus of term selection for creating the core source of vocabulary for the prototype ontology was the “searching” area. The knowledge engineering approach (Na and Neoh, 2008) was used to extract concepts and semantic relations. The criterion for extracting semantic relations from each concept pair was one-sentence statement, one-paragraph statement and one-page statement. Finally, the extracted relations were analysed by subject experts. Findings Based on the findings of this research, the possibility of using the methodology developed by Noy and McGuinness (2001) for building an ontology based on a Web-based thesaurus in the field of LIS was investigated and the prototype ontology (ASIS&TOnto) was constructed in the area of “searching”. Practical implications The primary implication of ASIS&TOnto is aligned with Web 3.0 research where implications of semantic modelling are a priority for community equity of access to information as a basic human right. ASIS&TOnto ends up with an ontology that is comprehensive, at least with respect to expressivity of the current ASIS&T thesaurus user interface definition languages; that is, it can be universal and can be extendable to future user interfaces that do not exist at the moment. Originality/value For the first time, a new enriched semantic tool (ASIS&TOnto) was constructed based on the ASIS&T Web-based thesaurus.