This study is a response to the current long-term policy effort aimed at reducing greenhouse gas emissions from aviation. It explores the short-term feasibility of servicing medium and long-haul commercial air routes with fully electric, zero-emission aircraft. The focus on long-haul flights reflects our understanding of the high levels of emissions associated with these routes. The analysis applies technical details of current electric aircraft development to the conditions faced by 183 long-haul over-water inter-city air routes. It also investigates the effect of future technical developments in battery power. Three scenarios of battery development illustrate how new electric aviation routes might evolve over time. Results show that, as expected, with current electric aircraft technology, most of the routes are more complex, slower, and more expensive than today's services. However, a significant number of simulated routes appear to be competitive in terms of fares with the current non-stop services. Furthermore, the simulations reflect conditions that existed in the early development of aviation and show that the expected evolution of batteries could increase the number of long-haul routes potentially served with electric aircraft. The study concludes that the immediate future of electric aviation might lie in selected, long-haul routes with low geophysical complexity and suggests that the methodology developed here could be used to evaluate proposals for services, some of which could be directed at smaller and remote locations.