People surfing the Internet are faced with an onslaught of messages from multiple sources, which can overwhelm receivers. In contrast to previous studies, which have used ‘choice overload’ to represent the amount of information provided to consumers, this study used ‘information overload’ theory to represent the abundance of information received by consumers in online shopping environments. Borrowing from the concepts of the communication model, this study investigated the antecedents of perceived information overload, including information characteristics (message), the information source, the system interface (channel) and recipients’ motivation (receiver). A total of 15 adults with more than 3 years of online shopping experience participated in a focus group discussion. By integrating focus group results and the results of previous studies into a theoretical framework, this study developed and empirically tested a structural equation model of online information overload among 456 PChome customers. The results indicated that the complexity and ambiguity of information characteristics, number of brand alternatives offered by the information source and system interface all positively affect consumers’ perceived information overload. Furthermore, information recipients’ motivation not only negatively affected consumers’ perceived information overload but also moderated the relationship between the number of brand alternatives and consumers’ perceived information overload.