<p>A thermal model was developed to parametrically evaluate, from the energy, exergy and exergoeconomic point of view, a power and heat cogeneration system that uses a co-fuel consisting of poultry litter and natural gas, with the aim of revaluing this waste from poultry farming activities. This is an analysis that has not been previously developed at this level of scope and that allows obtaining information that can be useful for decision-making regarding the design and operation of this type of system. A system consisting of a combustion chamber for co-fuel with a coupled Stirling engine for power generation and a heat exchanger for harnessing the energy of the combustion gases to heat water for heating was modeled. Due to the differences in composition that poultry litter from different poultry farms can present, three typical compositions were used to consider their effect on key system parameters. Some of the most important results show that using a higher percentage of poultry litter in co-fuel has a significant effect on reducing the specific exergy cost of the product, produces a moderate increase in exergy efficiency, but significantly reduces the energy efficiency of the system. It has also been demonstrated by this work that typical variations in the composition of poultry litter can negatively affect, in a non-negligible manner, the specific exergy cost of the product and energy efficiency, and when the power/heat ratio demanded by the system is greater, the exergy efficiency and specific exergy cost of the product improve, while the energy efficiency deteriorates significantly.</p>