The cost and logistics of building early hydrogen refueling infrastructure are key barriers to the commercialization of fuel cell vehicles. In this paper, we explore a "cluster strategy" for introducing hydrogen vehicles and refueling infrastructure in Southern California over the next decade, to satisfy California's Zero Emission Vehicle regulation. Clustering refers to coordinated introduction of hydrogen vehicles and refueling infrastructure in a few focused geographic areas such as smaller cities (e.g. Santa Monica, Irvine) within a larger region (e.g. Los Angeles Basin). We analyze several transition scenarios for introducing hundreds to tens of thousands of vehicles and 8-42 stations, considering: Station placement Convenience of the refueling network Type of hydrogen supply Economics (capital and operating costs of stations, hydrogen cost). A cluster strategy provides good convenience and reliability with a small number of strategically placed stations, reducing infrastructure costs. A cash flow analysis estimates infrastructure investments of $120-170 million might be needed to build a network of 42 stations serving the first 25,000 vehicles. As more vehicles are introduced, the network expands, larger stations are built and the cost of hydrogen becomes competitive on a cents per mile basis with gasoline. (C) 2011 Elsevier Ltd. All rights reserved.