Recent research on voluntary action control in our lab has focused on a) the impact of effort mobilization and reward on the speed-up of action control and b) the question of whether effort may be recruited to optimize response accuracy. In the present study, we systematically examined the ability to control temporal characteristics of our actions by instructing participants to voluntarily slow down response onset in a systematic manner. Participants were instructed to issue speeded (key release) responses in a baseline condition. Then, they were instructed to comply with specific target response times (e.g., 300, 400, 500 ms etc.) in blocks of trials based on trial-wise response time feedback. We then quantified the ability to voluntarily target these particular response times. The results indicate that shorter (vs. longer) target response times were associated with a systematic temporal overshoot, and that participants were about equally quick to comply with the target time across conditions. These data complement previous research on mechanisms of voluntary action modification by focusing on slowing down (instead of speeding up) temporal response parameters. The findings are additionally interpreted with regard to fundamental assumptions of two-system theories of action control, potentially challenging the underlying assumption of two qualitatively different response modes (fast and slow).