Students should read comfortably and at an adequate speed when doing ER. Reading duration, time-on-task, and effort are measures of reading engagement promoting reading comprehension. In the digital era, ER has shifted to online platforms. This study investigated the relationships between the reading speed, engagement, and reading comprehension of 34 Thai university students using XReading for six weeks. The time spent and number of activities were also collected using separate record forms. A Likert-scale questionnaire assessed the participants’ reading engagement. A Pearson r correlation revealed positive relationships between comprehension and indicators of reading engagement; namely, time-on-task (r = 0.62, p = 0.00), and reading engagement (r= 0.80, p=0.00) and reported no correlation for reading speed (r = -0.06, p = 0.77) and the numbers of activities (r = 0.08, p = 0.66). The implications for online ER practices and their limitations will be discussed.