Solid oxide fuel cells (SOFCs) have the capability to use hydrocarbon fuels and the potential to offer high efficiency and reliable power to many end users. Propane is a popular and readily available commercial fuel for a wide range of portable applications. This paper discusses various aspects of several propane-fueled and thermally self-sustained SOFC portable power systems, such as startup and shutdown characteristics, thermal cycling, load cycling, power output stability, effects of environmental temperatures and humidity on performance, and durability.