Promising electricity and hydrogen production chains with CO2 capture, transport and storage (CCS) and energy carrier transmission, distribution and end-use are analysed to assess (avoided) CO2 emissions, energy production costs and CO2 mitigation costs. For electricity chains, the performance is dominated by the impact of CO2 capture, increasing electricity production costs with 10-.0% up to 4.5-6.5 (sic)ct/kWh. CO2 transport and storage in depleted gas fields or aquifers typically add another 0.1-1(sic)ct/kWh for transport distances between 0 and 200 km. The impact of CCS on hydrogen costs is small. Production and supply costs range from circa 8(sic)/GJ for the minimal infrastructure variant in which hydrogen is delivered to CHP units, up to 20 (sic)/GJ for supply to households. Hydrogen costs for the transport sector are between 14 and 16 (sic)/GJ for advanced large-scale coal gasification units and reformers, and over 20 (sic)/GJ for decentralised membrane reformers. Although the CO2 price required to induce CCS in hydrogen production is low in comparison to most electricity production options, electricity production with CCS generally deserves preference as CO2 mitigation option. Replacing natural gas or gasoline for hydrogen produced with CCS results in mitigation costs over 100(sic)/t CO2, whereas CO2 in the power sector could be reduced for costs below 60 (sic)/t CO2 avoided. (C) 2007 Elsevier Ltd. All rights reserved.