This paper presents results from the international AcceptH2 study (http://miww.accepth2.com) of acceptability and preferences for hydrogen fuel cell (FC) buses. Using the contingent valuation method, this paper compares public willingness to pay (WTP) for the air pollution reductions associated with a scenario of large-scale introduction of hydrogen (H-2) FC buses in four cities: Berlin, London, Luxembourg and Perth. Results indicate that bus users in all cities have a positive WTP for H-2 buses, and that values (adjusted to the cost of living in each city) are very similar across geographical locations (ranging from WTP an extra E0.29 to E0.35 per single bus fare). Non-bus users were also interviewed in London and Perth, in order to capture values for the whole populations in these cities. Combined results for bus users and non-bus users confirm that overall residents in these cities are willing to pay extra (in taxes) to support the large-scale introduction of H-2-buses. (c) 2007 Elsevier Ltd. All rights reserved.