The aim of the paper is to analyse the illusion of knowing in metacognitive monitoring of the learning activity of university students (n = 262). The analysis focuses on the effects of the different types of information proposed and of personal, cognitive, metacognitive, and individual psychological characteristics of the participants. The research has shown that the illusion of knowing can occur in all types of metacognitive judgments, but is more evident in prospective judgments and depends on the type of information, its length and style, task type, etc. There are empirically established correlations between the selected personal, cognitive, and metacognitive characteristics. Gender and age differences in the manifestation of the illusion of knowing are not observed, although it is found that women tend towards overconfidence. The results also showed that the illusion of knowing is more typical for younger students, especially for those with lower levels of academic achievements.