The influence of emotions on decision making is widely accepted, however, research investigat-ing emotions within decision support systems is scarce. Previous research showed that via emo-tion regulation decision makers can significantly improve their decisions. However, a sound perception of emotions is a foundation for beneficial emotion regulation. In this paper, we pro-pose the use of live biofeedback–the provision of real-time information about a person’s current physiological state–as a potential feature for decision support systems in online environments. We developed a research model and hypothesize that live biofeedback can moderate (i) the in-fluence of the decision environment on decision makers’ physiological states and (ii) the deci-sion makers’ perceptions of their emotional states. Within the current research a live biofeed-back prototype for decision support in the context of financial trading was implemented. We aim at testing the hypothesized moderating effects of the developed decision support system in the controlled environment of a laboratory market experiment.