There is increasing interest in converting waste streams into electrical power, heat or useful fuels and chemicals such as hydrogen, methane and ammonia. Solid Oxide Cells (SOCs) are high temperature (500-1000°C) energy conversion devices which offer a high efficiency and flexible way to achieve these types of conversions. They are ideally suited to stationary applications and are capable of utilising a wide range of fuels and feedstocks including hydrogen, natural gas, waste gases and waste heat. The aims of my research are to investigate the chemistry of fuel and feedstock processing in SOC devices running in fuel cell and electrolysis mode in order to increase their performance, durability and economic viability. In particular, my research focusses on the effects of fuel variability and fuel contaminants on the behaviour and outputs of SOCs running on gases derived from biomass and waste streams.