This study is focused on the province-wide emissions in Ontario, Canada and urban air pollution in the city of Toronto. The life-cycle (LC) impacts of utilizing alternative fuels for transportation purposes is considered in terms of six major stressors for climate change, acidification and urban air quality. The vehicles considered are plug-in hybrid electric vehicles (PHEVs), fuel cell vehicles (FCVs) and fuel cell plug-in hybrid electric vehicles (FCPHEVs). Modeling of the penetration rates for these types of vehicles has been completed based on the maximum base-load capacity of Ontario's electricity grid to accommodate the generation of hydrogen and charging of vehicles using grid electricity. Results show that the reduction in greenhouse gas emissions from adoption of PHEVs or FCVs will exceed 3% of the current emissions from the transportation sector in Ontario while FCPHEVs may achieve almost twice this reduction. All vehicles exhibit similar impacts on the precursors for photochemical smog although the province-wide effects differ significantly. (C) 2009 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.