As an important tool for STEM education, online labs have gained significant research attention. However, our understanding of online labs is limited by the inattention to the factors that contribute to the acceptance of online labs. This study adopts the UTAUT model to investigate the salient determinants of use of online labs. We test the proposed research model with data from N = 194 students. We find that performance expectancy, effort expectancy, and social influence are positively related to behavioral intention. Behavioral Intention, in turn, is positively related to use. In contrast, the association between facilitating conditions and use is not significant. In terms of the moderating links in the research model, age did not moderate any of the four links (performance expectancy and behavioral intention; effort expectancy and behavioral intention; social influence and behavioral intention; facilitating conditions and use) and gender did not moderate any of the three links (performance expectancy and behavioral intention; effort expectancy and behavioral intention; social influence and behavioral intention). The three variables (performance expectancy, effort expectancy, and social influence) explain 61.4% of variance in behavioral intention. In contrast, the two variables (behavioral intention and facilitating conditions) explain only 15.7% of variance in use.