The perception of mobile payment procedures’ security by the customer is one major factor for the market breakthrough of the according systems. In this paper we examine security issues in mobile payment from the viewpoint of customers. Based on theoretical research we analyze empirical data from the MP2 mobile payment study with 8295 respondents in order to develop a set of dimensions, categories and aspects. The results do have a scientific as well as a practical impact: They provide a basis for the selection of appropriate indicators for further empirical studies. Furthermore they can serve as a guideline for mobile payment service providers in order to prevent security concerns through appropriate design and communication of payment procedures and to convince customers of the security of their mobile procedures by meeting concerns in informative advertising.