The aim of this study is to test the discriminative capacity of executive function (EF) tasks to better define the cognitive functioning of children with ADHD and comorbidities. One hundred four children were presented with a battery of new EF tasks and a rating scale filled out by parents. Preliminary analysis of the neuropsychological tasks revealed the presence of five factors: Speed of Processing, Inhibition, Planning, Execution, and Retrospective Memory. All children with ADHD were impaired in Execution (a measure describing the capacity to achieve a goal). ADHD-only children were specifically impaired in Planning, while ADHD + reading disorder (RD) children were impaired in Speed of Processing and Retrospective Memory. Children with ADHD + oppositional defiant disorder (ODD) did not show impairment in any other EF domains. The five EF processes correlated with the EF Questionnaire. The present study describes different cognitive profiles in children with ADHD with or without comorbid disorders using neuropsychological EF measures.