As the online shopping industry grows, more and more consumers are engaging in online impulse purchases.However, very few studies have explored the underlying causes behind this phenomenon. Based on the StimulusOrganism-Response framework, this research proposes two factors: presentation mode and product type which affectconsumer’s emotional states (pleasure and arousal), and lead to impulse buying decisions. We also investigate themoderating effects of product involvement and impulse buying tendency. A 2x2 laboratory experiment is conductedthat includes product presentation mode (virtual product experience and static image) and product type (hedonic andutilitarian) to test several hypotheses. Our study indicates that online retailers need to take special care when marketingutilitarian products. For utilitarian products, offering a high quality web design interface and taking steps to enhanceconsumers’ product involvement are important for eliciting positive emotions and ultimately inducing an impulsebuying decision.