Cloud environments are being increasingly used for the deployment and execution of complex applications and particularly componentbased ones. They are expected to provide elasticity, among other characteristics, in order to allow a deployed application to rapidly change the amount of its allocated resources in order to meet the variation in demand while ensuring a given QoS (Quality of Service). However, establishing a correct elastic component-based application is not guaranteed in Cloud. Indeed, applying elasticity mechanisms should preserve functional properties and improve non-functional properties related to QoS, performance and resource consumption. In this paper, we propose an approach for the verication and deployment of elastic component-based applications. Our approach is based on the Event-B formal method. In fact, we formally model the component artifacts using Event-B and we dene the Event-B events that model the elasticity mechanisms (scaling up and down) for component-based applications. Furthermore, we formally verify that our approach preserves the semantics of the component-based applications by using the Proof Obligations and the ProB animator. Once the elastic component-based applications are validated, they can be deployed in a Cloud environment using an elastic deployment framework which we have developed