Keywords: XML, financial transactions, fuzzy logic, fuzzy XML, XML security, XML encryption, financial transactions, bankingThe eXtensible Markup Language (XML) has been widely adopted in many financial institutions in their daily transactions; this adoption was due to the flexible nature of XML providing a common syntax for systems messaging in general and in financial messaging in specific. Excessive use of XML in financial transactions messaging created an aligned interest in security protocols integrated into XML solutions in order to protect exchanged XML messages in an efficient yet powerful mechanism. However, financial institutions (i.e. banks) perform large volume of transactions on daily basis which require securing XML messages on large scale. Securing large volume of messages will result performance and resource issues. Therefore, an approach is needed to secure specified portions of an XML document, syntax and processing rules for representing secured parts.In this research we have developed a smart approach for securing financial XML transactions using effective and intelligent fuzzy classification techniques. Our approach defines the process of classifying XML content using a set of fuzzy variables.Upon fuzzy classification phase, a unique value is assigned to a defined attribute named "Importance Level". Assigned value indicates the data sensitivity for each XML tag.This thesis also defines the process of securing classified financial XML message content by performing element-wise XML encryption on selected parts defined in fuzzy