This research investigated the impact of complexity on the effectiveness of intuition in decision making. Empirical experimental research was conducted to examine the relationship between the use of intuition and decision accuracy, and how this relationship could be moderated by individual differences such as faith in intuition and cognitive reflection. Software purchase decisions were used as the context for the study because of the inherent complexity of the decision and anecdotal evidence that rational techniques are not always used. Dual-process theory was used as the theoretical lens for the research, which was conducted using an experimental manipulation of the use of intuition. The research made an original contribution by investigating complexity as a moderator, by examining the role of individual differences as other researchers have proposed, and by utilising bias measures as a proxy for decision accuracy in order to avoid the normatively correct choice measures that have been highlighted for their limitations. The results showed that intuitive decisions were less accurate in the software selection context, and that complexity does moderate this effect on decision accuracy, with intuition showing lower accuracy in simple decisions, but similar results in complex decisions. Faith in intuition and cognitive reflection did not show interaction effects, but there was a significant direct positive relationship between cognitive reflection and decision accuracy. The practical implications of this research include prescriptions for the conditions under which intuitive decisions can be appropriate.