The aim of this research was to investigate the effect of cooperative error detection in an online context on ESP students' writing accuracy and their attitudes towards cooperative error correction. To achieve this aim, the researchers selected 60 ESP students after homogenization. The Barratt Impulsivity Scale (Barratt, 1995) was administered to the participants. The researcher randomly assigned the participants to two groups: the experimental group (n=30, reflective=13, impulsive=17) and the control group (n=30, reflective=13, impulsive=17). The experimental group received the intervention for ten sessions. Skype was used in this group. The participants in this group were divided into six groups of 5 members each. Then, in each session, the students were given a descriptive topic and they were supposed to write and share their writing in their groups. Other members of each group had to check each member's writing and, in case of a problem, underline the mistakes and share them with the group. Finally, they sent the revised writing to the teacher. In the control group, the participants had to write about the same descriptive topic. They wrote and gave their writing to the teacher who corrected it. The results showed that the participants in the experimental group performed significantly better than those in the control group. In terms of learning style, both reflective and impulsive ESP students benefited equally from the intervention. In addition, participants in the experimental group who received the treatment had a positive attitude towards cooperative error detection, seeing it as something positive and fun. پرونده مقاله