The first Polish micro-combined heat and power unit (micro-CHP) with solid oxide fuel cells (SOFC) was designed and constructed in the facilities of the Institute of Power Engineering in Warsaw. The system was launched in September 2015 and is under investigation. At the current stage the unit is customized to operate on a pre-treated biogas. Adaptation of the fuel processing system, which is based on a steam reformer, makes it possible to utilize other gaseous and liquid fuels, including natural gas. The electric and thermal output of the system, up to 2 kW and about 2 kW, respectively, corresponds to the typical requirements of a detached dwelling or a small commercial site. Functionality of the system was increased by engaging two separate start-up modules, which are used for preheating the system from a cold state to the nominal working conditions. The first module is based on a set of electric heaters, while the second module relies on an additional start-up burner. The startup of the system from ambient conditions up to a thermally self-sufficient stage takes about 7 hours using the electric preheaters mode. Output residual heat was used to heat water to a temperature of about 50°C. The temperature of the flue gases at the inlet to the hot water tank was measured at approximately 300°C. Steam reforming of the biogas was performed by delivering deionized water to the steam reformer in order to maintain the S/C ratio at a range of 2–3.5. Selected aspects of the design and construction as well the first operational experiences are presented and discussed. The numerical modeling methodology is presented as a complimentary tool for system design and optimization.