Cogeneration systems are mainly used in industrial power plants (combined heat and power plants), but based on the analysis car-ried out in this publication, that suitably adapted and selected devices will be able on board of ships. A number of arguments have been obtained for using the indicated gas engine in a vessel. The cogeneration system guarantees high overall efficiency, as shown in the example of the cogeneration unit under study, for which the value of general efficiency was above 80%. In addition, the use of natural gas as a fuel could ensure a significant reduction in the amount of toxic compounds emitted to the atmosphere, especially nitrogen oxides (2-3 times) and smog (dust with PM10) around 25 times than standard limits. The use of natural gas as a fuel guarantees similar dynam-ic parameters as with the use of standard fuels.