The issue of security is paramount for the success of mobile business. Although the state of wirelessness offers portability, and therefore mobility, it adds to the risk of unauthorised access to the system and data disclosure. This chapter discusses how public key infrastructure (PKI) technology can be implemented to reduce the risks associated with mobile business. A theory of portable PKI (PORTABLEPKI) developed in this chapter within the context of Australian industries is to promote PKI technology for enhancing the security of mobile business. A framework for testing PORTABLEPKI theory and future research opportunities which will open up as a result of this developmental study are also provided.