Purpose: The ability to produce expository discourse (the use of language to convey information) is important for classroom participation and access to the curriculum, particularly during the middle school years. This study investigated the spoken expository discourse skills of students with reading comprehension (RC) difficulties compared to their peers with average reading skills. Method: In this study, we administered a modified favourite game or sport (M-FGS) task developed by Heilmann and Malone to 48 students who were in their fifth year of schooling (9.33 − 11.11 years of age). Expository language samples were transcribed and analysed on measures of (a) microstructure: syntax (MLU in words) and vocabulary (number of different words [NDW]); and (b) macrostructure (Expository Scoring Scheme [ESS]). Result: Compared to their peers with average RC skills, students with RC difficulties demonstrated significant difficulties at the micro- and macro-structure levels. Subgroup analysis revealed the importance of spoken language comprehension proficiency (at text level) for expository discourse skills. Conclusion: The results from this small-scale investigation demonstrated the usefulness of the M-FGS task in describing challenges in expository discourse of students with RC difficulties, with clear implications for intervention.