The simultaneous influence of increasing oil scarcity, greenhouse gas control and renewable energy targets will result in a future of sustained energy prices. Whether modern economies can find a smooth path away from fossil fuels is a fundamental socio-economic and political question, which according to standard economics depends to a large extent on the degree of substitution between energy and capital. We study this issue by modelling the manufacturing sector with a translog cost function in seven OECD countries using the EU-KLEMS database for the period 1970–2005. After a literature survey, different production structures accounting for input substitution, returns to scale and technical change are estimated, and substitution elasticities are derived. Our results indicate a general complementarity or weak substitution relationship between energy and capital, suggesting that an increase in energy price, e.g. due to climate policy or scarcer fossil fuels, will likely reduce capital inputs, which might lead to a lower output of manufacturing.