Many formal modelling notations for business processes have been proposed during the last decade. They can be broadly classified into high-level visual notations, with an intuitive meaning, mainly addressed to the business management community and low-level foundational notations, with a detailed and formal semantics, mainly addressed to the computer science community. Role activity diagrams are a popular high-level visual notation for capturing the dynamics and role structure of an organization. This paper establishes that role activity diagrams have a formal semantics as well and thus making them suitable to formal verification. The result is obtained by mapping of a role activity diagram model to a process algebra model. Process algebras are mathematical languages for the specification and understanding of concurrent and cooperating computational processes.