In recent years, emerging Information and Communication Technologies have changed the nature and process of decision making. Decision processes are often distributed, heterogeneous and subject to change. Business process modelling is a key technology for analysing, representing and executing business processes. It can be used to study distributed decision processes and improve decision making practices. A theoretical model of the decision process has been developed in order to better integrate the decision concept with models of business processes. The decision model is executed using a process support system that provides a distributed Web user interface. The enacted decision model evolves as the decision process progresses and supports decision makers if and when needed. The case study of an actual decision process undertaken in a not-for-profit organisation is presented to highlight the use, execution and validation of the decision model.