The creation of inter-organizational workflow implies the coalition of partners' efforts and resources in order to achieve a set of common objectives and goals. However, this openness may cause a huge damage to the participating entities due to security breaches. The risk of unsuccessful collaboration should be well studied. Thus, the key for successful collaboration is to select the appropriate collaborators based on specific security criteria for each outsourced task. In this sense, several criteria have to be considered, among them: trust and reputation level, policy similarity level, security level and privacy compliance level. The proposed security based partner selection approach allows us to rank participating entities in the collaboration based on the main security criteria in order to assign each task to the suitable partner with the most appropriate and efficient way.