A large number of studies conducted to investigate business-to-consumer e-commerce have focused exclusively on individual online shopping, but consumers often desire to conduct their shopping activities with others. This study explores the important yet understudied research area of collaborative online shopping. We investigate the design issues of an online collaborative shopping support tool and its impact on web consumers' attitude formation and intention to adopt online collaborative shopping. In particular, we examine two important functions of an online collaborative shopping support tool, namely collaborative browsing support and instant voice chatting support. We propose these two functions will positively affect the perceived ease of use and perceived usefulness of an online collaborative shopping support tool, and shopping enjoyment and telepresence in online collaborative shopping. These four factors are expected to positively affect web consumers' attitudes towards online collaborative shopping and their behavioral intention. A two by two mixed factorial design was used to test the linkages proposed above. We recruited sixty-four pairs of participants to participate in a laboratory experiment. The results indicate that collaborative browsing support increases a web consumer's perception of usefulness of an online collaborative shopping support tool; collaborative browsing support increases shopping enjoyment and telepresence in online collaborative shopping; and perceived ease of use of the browsing support tool is not supported. Instant voice chatting support increases perceived ease of use and perceived usefulness of an online collaborative shopping support tool, and shopping enjoyment and telepresence in online collaborative shopping. Perceive usefulness, and shopping enjoyment are important in improving consumers' attitudes towards online collaborative shopping and their intention to shop together with friends online. This research addresses a gap in our current understanding of web users' behavior. The implications of the research for both researchers and practitioners are discussed.