The work is a case study of a cruise ship supplied by liquefied natural gas (LNG) and equipped with a solid oxide fuel cell (SOFC). It is supposed that a 20 MW SOFC plant is installed on-board to supply hotel loads and assisting three dual-fuel (DF) diesel/LNG generator sets. LNG consumption and emissions are estimated both for the SOFC plant and DF generator sets. It results that the use of LNG-SOFC plant in comparison to DF generator sets allows to limit significantly the SOx, CO, NOx, PM emissions and to reduce the emission of CO2 by about 11%. A prediction of the weight and volume of the SOFC plant is conducted and a preliminary modification of the general arrangement of the cruise ship is suggested, according to the latest international rules. It results that the SOFC plant is heavier and occupies more volume on board than a DF gen-set; nevertheless, these features do not affect the floating and the stability of the cruise ship.