The study evaluated online reference services through social networking sites in selected university libraries in Nigeria. A survey approach was embarked upon to ascertain patrons’ level of awareness, their preference, source from which they were inform of existence of the service, effectiveness of the service and their level of satisfaction with online reference service through social networking sites in their libraries. The targeted population for the study includes undergraduates of University of Ilorin, Nnamdi Azikiwe University and University of Benin with a total population of 64,770. A sample size of 394 was drawn from the study population using Simple sampling technique. A survey questionnaire was design for collection of data. The instrument was divided into 2 sections. Section (1) of the questionnaire contains the bio-data of the respondents while section (2) handles the subject matter listed in alphabet A-F. It was a close ended questionnaire. Each question asked in section two of the questionnaire was tailored toward answering the research questions in order to achieve the objective of the study. The findings reveal that many patrons are aware of the fact that their university libraries are on social networks, and yet not familiar with reference services. Facebook, Twitter and Ask a Librarian are ranked as most preferred in delivery of online reference services. Most respondents gain an awareness of the services through their friend. Respondents agree that an online reference service is more convenient than traditional desk reference service in that it encourage anywhere, anytime communication with reference librarian due to easy accessibility. Findings also reveal that the services is not all that effective as there are low level of awareness, which is the reason why the service recorded not so many utilization from patron, subsequence of which led to a fair satisfaction from users. In relation to this, the study reveal that the rate at which patrons patronized the services was influence by their level of awareness of the services in their libraries. This study innovatively addressed contemporary issues concerning the evaluation, and ultimately, the relevant of online reference services in academic libraries. It is of great benefit to academic libraries and patron alike as the study identifies ways to increase the visibility and use of online reference service in Nigerian university libraries.
