Purpose: The purpose of this paper is to present the results of measuring a sample of engineering students' perceived achievement of complex thinking at different stages of their professional training. This study intended to analyze and predict the differences in the self-perception of achieved complex thinking competency by gender, semester, course of study and high school of origin. Design/methodology/approach: The methodology included applying the E-Complexity instrument to 225 university students from northern Mexico. The initial comparison of groups used the chi-square test and two supervised learning algorithms (logit regression with Lasso regularization and a classification tree). Findings: The findings of this study indicated that the selected undergraduate degree did not reveal differences in self-perceived performance in complex thinking, while gender, semester and high school of origin had significant differences. Research limitations/implications: Among the limitations of the study is the size of the sample and the fact that it only focused on engineering students from a single educational institution; however, this limitation responds to the exploratory nature of this study and the guidance of the institutional ethics committee. With these results, it is feasible to request an extension of the sample to include other disciplines to evaluate these findings, which, although relevant, cannot be considered exhaustive. Originality/value: Regarding possible lines of research, the authors propose that given the difference between students who graduated from the high school of the same institution and those who did not, a possible line of research could explore new hypotheses on whether the policies and practices of the institution's high school emphasize the development of complex thinking skills; the teachers of this high school are trained to teach complex thinking; and the learning materials of this high school are designed to develop complex thinking skills.