The aim of this study is to investigate the effectiveness of the Comprehension Strategies Mobile App (COSMA) on the reading comprehension performance of students with learning disabilities. Four students with learning disabilities (three boys, one girl) participated in the study. The experimental process of the study was carried out according to the multiple baseline across participants model of single-subject experimental designs. Reading comprehension performance of students was assessed with multiple-choice tests and retells. Students' use of strategies was evaluated with on-task metacognitive interviews. Findings showed that COSMA has a positive impact on students' reading comprehension performances. It was determined that the students' motivation to use the mobile app was high, the opinions of families and teachers of the software were positive and they observed an increase in students' reading skills. Findings are discussed further.