The study investigated the behaviours of critical thinking skills among UKM students. This study involved 200 UKM students as research participants. Respondents were from Bachelor students (Year 1 to Year 4), and Master students. The location of this study is in Bangi Campus, UKM that includes seven faculties. Those are Faculty of Social Sciences, Faculty of Education, Faculty of Islamic Study, Faculty of Management and Economics, Faculty of Science and Technology, Faculty of Science and Information Technology and Faculty of Engineering. The students’ age range is between 19 to 46 years old. The instrument used to measure the attitude of critical thinking skills is California Critical Thinking Skills Test (CCTST), that was translated by the researcher into Malay language. In addition, this research also employed descriptive and inference statistics analyses in the form of mean score, standard deviation, percentage, frequency, Pearson Correlation, non-parametric Kruskal-Wallis and T-Test. The result showed that the behaviour of critical thinking skills was not related significantly with UKM students’ academic performances. Cognitive maturity behaviour influenced their academic levels from low and moderate to high performance. Finally, male and female students also differ in their open-mindedness, objectivity, readiness to face challenges and desire to seek the truth.