Workflow technologies are becoming pervasive in that they enable the execution of business processes in distributed and ubiquitous computing environments. The execution of pervasive workflows raises transactional requirements due to their dynamicity and the need for relaxed atomicity. In this paper, we propose an adaptive transactional protocol for the pervasive workflow model developed in a previous work. The execution of this protocol takes place in two phases. First devices are assigned to tasks using an algorithm whereby workflow partners are selected based on functional and transactional requirements. The workflow execution further proceeds through a hierarchical coordination protocol managed by the workflow initiator and controlled based on a decision table computed as an outcome of the device assignment procedure. The resulting workflow execution is compliant with the defined consistency requirements and the coordination decisions depend on the transactional characteristics of the devices assigned to each task.