This working paper discusses the potential of zero-emission technologies to reduce emissions from non-road transport, including aviation, maritime, off-road, and rail. These modes represent a quarter of transport-related greenhouse gas emissions and pose significant local pollution issues, but policy regulating emissions for these vehicles has been slow-moving and fragmented. Based on demonstrations, pilot projects, and available research literature, this working paper evaluates the benefits and barriers to the adoption of various zero-emission technologies in each sector and discusses policy implications.