The Worst-Case Execution Time (WCET) analysis is an important stage in development process and verification of hard real-time systems. In this article the use of XML as a standard for exchanging timing information amongst timing analysis tools is proposed. Timing information resulted from automatic analysis of programs can be represented in XML format. Considering the type of information required for estimating the worst case execution time of programs, a set of XML tags is offered in this paper. Timing information resulted from analyzing a program by a timing analysis tool could be annotated within the program. The annotated code could be simply applied by other tools for relatively more accurate estimation of the worst case execution times. The paper also clears the way for future studies on using XML-based representation for extraction of information.