To adapt to novel socio-dynamic events, a balance between response execution and action inhibition is imperative. Even though accumulated evidence indicates inhibitory control deficits in neurodevelopmental and substance abuse disorders, the neural underpinnings remain unknown. To address this, comparative studies across primate species are crucial. Although common marmosets (New-world monkeys) are among the most suitable animal models for translational research on neurodevelopmental disorders, their inhibition ability (in the context of a Stop-task paradigm), have not been thoroughly investigated. Therefore, we trained 4 marmosets in a specifically designed marmoset Stop-signal task, in which response time was measured at millisecond resolution.Marmosets performed many repeated Go trials with high accuracy (³70%) and learned to inhibit their response when it was explicitly instructed. Using a performance-dependent tracking procedure, we estimated marmosets’ stop signal reaction time (SSRT) at millisecond resolution. The mean SSRT values across sessions ranged between 677 ms to 1464 ms across the 4 marmosets. We also examined the effects of intranasal oxytocin on response execution and inhibition. Our results indicated that oxytocin enhanced both response execution and inhibition, as marmosets exhibited a faster RT in Go trials and a shorter SSRT in oxytocin sessions compared to control (saline) sessions. This marmoset model, for assessing the balance between response execution and inhibition, will further facilitate exploring the neurodevelopmental alterations and the effects of contextual and environmental factors on executive functions.