International Journal of Web Applications Kokila Harshan Ramanayaka, Xianqiao Chen, Bing Shi 10 4 2018 10.6025/ijwa/2018/10/4/137-153 http://www.dline.info/ijwa/fulltext/v10n4/ijwav10n4_3.pdf A library website plays an enhanced role compared to its traditional physical library while providing a wide variety of library services to its users. Evaluation of library websites is a key to realize the extent of user acceptance to the website and to improve overall quality of website. Usability is a highly recognized factor to determine how easy to use the website. The models of usability evaluations evaluate the ease of use of website operations and see whether the users can perform their tasks easily. Moving on further, this study has been undertaken in context of library websites in Sri Lanka with the main purpose of exploring the favourable weights of the seven key dimensions and 20 measuring items with the aids of experts in the related field. These dimensions and measuring items were identified from our previous study which have been tested its reliability and validity in assessing library website usability in Sri Lanka with the aids of actual library users in Sri Lanka. Fuzzy theories together with the extent analysis fuzzy analytic hierarchy process method were applied. It was expected to identify the relative importance of the criteria of interest while avoiding uncertainty, ambiguity, loss of data, and difficulties faced in assessment cycle. Triangular fuzzy numbers were used to represent the judgments on the relative importance between each pair of factors that makes experts consensus uniform rather than using linguistic values. The research findings concluded that satisfaction was the dimension that the experts considered most important in evaluating library website usability. The experts rated accessibility as the least important dimension.