Nowadays, a growing number of companies are using Cloud Computing to optimize their business processes by using dynamically scalable and often virtualized resources on demand. Nevertheless, due to the lack of explicit and formal description of the resource perspective in existing business processes, Cloud resource allocation behavior cannot be efficiently and correctly managed. In this paper, we aim at formally verifying resource allocation in business processes using Event-B. More precisely, our aim is to specify the resource allocation behavior both at design time and at runtime, and to check its correctness according to users' needs. Our model also takes into account different cloud properties such as elasticity and shareability. In order to show its feasibility, our approach has been tested using a use case study from an industrial partner