Problem posing is an indispensable constituent of mathematical thinking, which makes it a requisite ability for students of all grades. Therefore, pre- and in-service teachers should carry out problem posing activities of high quality, and having them pose non-routine problems may be a good way to make this happen. In this context, this study intends to examine prospective middle-school math teachers' performances and emotions in non-routine problem posing, as well as to investigate whether there is any relationship between these two variables. The study was carried out with 64 prospective teachers in the scope of an elective course about problem solving. Data sources were created problems and questionnaires collected from the participants. The former was used to evaluate success while the latter was employed for describing emotions. According to the results, the participants were moderately successful in designing non-routine problems. As for emotions, although the participants mostly acknowledged the merit of posing non-routine problems, they found it very demanding as well. Besides, the interplay between performance and emotions in non-routine problem posing was low. The results indicate that prospective teachers have the potential to generate non-routine problems, and are predominantly positive toward this skill.