Purpose Frustration is an emotion often clinically reported by persons who stutter. So far, mainly questionnaire-based studies have reported findings related to increased frustration or decreased frustration tolerance. The aim of this preliminary study was to determine possible group differences between children who stutter (CWS) and children who do not stutter (CWNS) using a behavioral experimental task, as well as to evaluate possible associations with the frequency, duration, and physical concomitants of stuttering disfluencies. Method Participants were 13 CWS (mean age = 6;05 years) and 13 CWNS (mean age = 6;06 years), matched on age (±4 months) and gender. Frustration tolerance was assessed by the Delay Frustration task. This task includes normal delay, short delay, and long delay trials. Responses during long delay trials provide an indication of frustration tolerance and were recorded across time intervals during the response window. Results CWS, compared to CWNS, responded more frequently during the long delay trials, which is indicative of higher delay frustration. The variation in responding across time within intervals was similar for both groups. Decreased frustration tolerance was associated with increased duration of stuttered disfluencies and of physical concomitants. Conclusions In general, the current findings seem to provide support for earlier theoretical conceptualizations about the role of emotional reactivity in the development of stuttering.