Delay Tolerant Networks are a class of wireless networks that has recently attracted a lot of attention from the networking community. They are characterized by frequent network partitioning, intermittent connectivity, long and variable delays, high error rates. Such performance challenging conditions are usually found in environments populated by a sparse set of fixed or mobile nodes with limited communication capabilities. The store-cany-and forward principle, according to which messages can be stored at mobile nodes moving around the network area before being forwarded to the destination, has emerged as the new communication paradigm for delay tolerant networks, demanding novel performance evaluation tools and methodologies with respect to rhose developed in traditional store-and-forward packet networks. In this paper, we describe an analytical framework to study Delay Tolerant Networks, based on model checking techniques. In particular we employ the logic asCSL as a poweful formalism to define specific peformance metrics suitable to analyze the behavior of these systems.