Only few studies have examined the relationship between problematic Internet use (PIU) and cognitive and academic performance in adolescents. The aim of this study was to analyze the differences in academic and cognitive performance (perception, attention, memory, verbal fluency and abstract reasoning) between adolescents with and without PIU. A total of 575 students from different high schools of the region of Alicante participated. Students were divided into two groups: adolescents with and without PIU (PIU and NPIU, respectively). Several questionnaires were administered to assess problematic Internet use, as well as students' academic performance. Substance use (alcohol / cannabis) was also assessed as exclusion criteria. A battery of neuropsychological tests was used to assess cognitive abilities. On the one hand, PIU users group obtained poorer academic results than NPIU, in terms of lower marks and more failed subjects. On the other hand, PIU group had a better hit ratio in the perception test than NPIU group. However, PIU adolescents got higher error rates for the abstract reasoning test. This greater number of errors, plus a similar number of hits compared to the NPIU group, could indicated a higher response rate for the PIU group, which may might be associated with greater impulsivity. As occurs in other addictive and non-substance-related problems studies, these results could mean difficulties in impulse control and regulation of response inhibition circuits in PIU users group. Future research is needed to analyze in depth the results presented in this paper.