Cloud federation has been emerged as a new paradigm in which group of Cloud Service Providers (SP) cooperate to share resources with peers, to gain economic advantage. In this paper, we study the cooperative behavior of a group of cloud SPs. We present broker based cloud federation architecture and model the formation of cloud federation using
coalition game theory
. The objective is to find most suitable federation for Cloud SPs that maximize the satisfaction level of each individual Cloud SP on the basis of Quality of Service(QoS) attributes like availability and price.