The subject of this paper is the use of natural gas as a fuel on ships. The paper is structured in 7 chapters which deal with the advantages and disadvantages of gas as a fuel with reference to the increasingly stringent regulations of the International Maritime Organization. The first part of the paper under the chapter "Introduction" explains the subject of the paper in general. Then, in the second and third parts, under the chapters “Natural gas deposits and use” and “Natural gas”, the history and deposits of gas and its physical properties are analyzed. The fourth chapter "Transport and liquefaction" explains the procedures for transporting gas from liquefaction plants as well as the liquefaction processes themselves. Chapter 5 “Natural Gas Storage” deals 3 with the types of gas storage and bunker processes. The sixth chapter, entitled “Using LNG as a Fuel”, analyzes the various propulsion systems that use natural gas in the ship’s propulsion cycle. The last chapter "Switching to LNG as a fuel" analyzes the advantages and disadvantages of gas in terms of environmental impact and efficiency of propulsion systems.