There are many advantages to the use of peer marking to student learning, but when used with code creation it has the added advantage that it mirrors one of the key activities undertaken with code, the reusing of others’ code. Due to the range of roles that chemical engineers can undertake and the increasing use of modelling, it is becoming more important to include skills like this within degree courses. However, if peer-marking is to be used effectively it is important that the marks generated from it are reliable and the feedback generated from peers is useful.This paper examines the use of peer marking to allow students to develope their use and knowledge of molecular dynamics. Each student is provided with codes to mark and a rubric which guides their marking. The rubric contains information about the code format and using the code for some calculations.The marks given by the students are consistent with marks checked by the course leader, especially when the student marks are averaged when code is multiply marked. For the averaged mark the effect size between the student mark and the tutor mark is only 0.12 and the Pearson product correlation coefficient is 0.82. Students also received helpful feedback from their peers.