Long-Running transactions consist of tasks which may be executed sequentially and in parallel, may contain sub-tasks, and may require to be completed before a deadline. These transactions are not atomic and, in case of executions which cannot be completed, a compensation mechanism must be provided. In this paper we develop a model of Hierarchical Timed Automata suitable to describe the aspects mentioned. The automaton-theoretic approach allows the verification of properties by model checking. As a case study, we model and analyze an example of long